Oct 12, 2026Reference & Sizing
Watch Band Link Pin Size Guide: Measuring, Types, and Refill Assortments
Loose links are a pin problem: cotter, pin-and-tube, screw tube and threaded link pins. Identify the family, measure, and match it to a refill assortment.
Watch Band Link Pin Sizes: Pin Problems Versus Spring Bar Problems
When a bracelet separates or a clasp opens, the failure is almost always a loose or sheared link fastener, not a broken band. Before ordering hardware, distinguish link pins from spring bars. Spring bars anchor the bracelet to case lugs; link pins join individual links and clasp hinges. If your strap detaches at the lugs, you need the spring-bar side of the problem—see our Seiko 5 SNK spring bar size guide. Kocandy supplies replacement pins and assortments; we do not sell finished straps or assembled bracelets.
Fastener Families: How Friction Pins, Cotter Pins, and Screw Rods Hold
Metal bracelets rely on three mechanical retention methods. Split cotter pins use spring tension: folded stainless steel legs compress inside the link bore and push outward to stay seated. Pin-and-tube systems use an interference-fit collar tube that grips a smooth center pin. Screw tube rods and threaded pins use machine threads, either engaging a female sleeve or threading into tapped link walls. Identifying your fastener family dictates the correct tools and prevents damaged link bores.
Type | How it holds | Where used | Catalog kit |
|---|---|---|---|
Split cotter pins | Spring friction from split legs compressing inside link hole | Folded metal links, stamped fold-over clasp links, entry solid links | 400-piece cotter pin assortment (5–24 mm) |
Pin and tube (collar) | Solid pin pressed into center/end collar tube providing outward grip | Heavy solid bracelet links, dive watch expansion links, rubber straps | 150-piece pin and tube assortment (tube 1.2 x 5.9 mm) |
Tube friction bars with rivet ends | Hollow central tube friction-fitted over knurled or rivet end caps | Bracelet clasp hinges, safety foldover buckles, hooded lugs | 100-piece friction bar set with 1.5 mm rivet ends |
Screw tube rods (female tube + male cap) | Male threaded end cap turns into hollow female tube rod | Reinforced bracelet links, heavy lug hinges, diver bracelet links | 50-piece 10-size and 60-piece 12-size screw tube kits |
Solid threaded screw pins | Single solid pin with threaded tip engages tapped thread in outer link | Solid metal bracelets, multi-link and five-link bands, luxury-style bracelets | 90-piece 18-size assortment listed for Rolex-style bands |
Split Pins and Cotter Bars for Metal Bracelet Links
Split cotter pins are standard hardware for folded-link bracelets and entry steel bands. Formed from doubled-over stainless steel wire, a cotter pin features a bulbous head and two parallel shafts. Drive the pin out toward the stamped arrow, and insert the smooth end first from the opposite side.
Our catalog provides a watch band link cotter pin assortment covering stated lengths from 5 mm to 24 mm in 1 mm steps. The listing specifies an approximate 1.0 mm head diameter, packaged as 400 pieces in 20 sizes (with catalog text also noting 360 pieces in 18 sizes). Select a length that seats flush with the link edge.
Assorted stainless steel cotter link pins in 20 stated lengths from 5 mm to 24 mm.
Pin and Tube Friction Systems for Heavy Straps and Clasps
Solid-link bracelets, dive extensions, and silicone straps frequently use pin-and-tube systems. A miniature collar sits inside the center link, providing friction while a smooth pin carries shear load.
Our catalog includes the 150-piece watch pin and tube set (model SP0003457), featuring a stated tube size of Φ1.2 mm x 5.9 mm and pin diameter of Φ0.9 mm across ten lengths from 10 mm to 28 mm (15 pieces per size). For clasps, the 100-piece watch tube friction pins and rivet ends assortment (model MABA-FG-SB-0010G) provides 1.0 mm tubes and approximately 1.5 mm rivet heads across ten lengths from 8 mm to 26 mm. Always verify collar presence before reassembly.
Tube friction pins with 1.0 mm stated tube thickness and 1.5 mm rivet ends.
Screw Tube Rods and Lug Stems for Threaded Links
Screw tube rods pair a hollow female sleeve with a threaded cap, bridging the joint bore while shielding links from thread wear.
Our catalog includes the 50-piece metal watch band screw tube rods set (model SP00002314), containing ten slotted sizes (5 pieces per size) with 1.0 mm to 1.4 mm tube diameters, 1.2 mm to 1.7 mm heads, and lengths from 10.5 mm to 26 mm. The 60-piece 12-size stainless screw tube rods assortment (model BDLS-RH-S-0001) covers spans from 8.5 mm to 19 mm. For lug stems, the 60-piece strap link tube rods and lug stem screws kit provides 3.5 mm heads on 1.5 mm tubes across ten lengths from 12 mm to 30 mm (6 pieces per size).
Ten-compartment box of 50 stainless steel screw tube rods in model SP00002314.
Rivet-End Screw Pins and Case-Lug Bar Sets
Rivet-end screw pins pair a fixed decorative head with a threaded cap, finishing both bracelet flanks cleanly.
Our catalog provides the 40-piece watch band screw pins with rivet end set in silver or rose gold, offering ten sizes (4 pieces per size) with 3.0 mm and 3.5 mm heads, 1.3 mm tube diameter, and lengths from 20 mm to 28 mm. A companion listing supplies black and gold rivet-end screw pins. Check dimensions carefully: the black and gold listing states 3.5 mm and 4.0 mm heads with 2.1 mm and 3.0 mm tube diameters across 20 mm to 28 mm lengths, unlike the silver and rose-gold set.
Threaded Link Screws and Brand-Listed Assortments
Solid-link bracelets often use single-piece threaded link screws. One outer link has a counterbored hole, the center link has a clearance bore, and the opposite outer link has tapped threads. The screw shank passes through and threads directly into the link wall.
For general replacement, our catalog features the 50-piece watch band screw link pins set, containing ten slotted sizes (5 pieces per size) with lengths from 10.5 mm to 26 mm. For specialized bracelets, our catalog supplies the 90-piece watch link screw pins assortment listed for Rolex-style bands. Made from 316 stainless steel, this set provides 18 sizes (S1 to S18, 5 pieces per size) with thread diameters from 0.80 mm to 1.4 mm, widths from 0.95 mm to 1.7 mm, and lengths from 8.6 mm to 19.4 mm. Always match shank width and thread diameter before installation.
Eighteen-size 316 stainless steel screw pin assortment listed for Rolex-style metal bands.
Bench Measurement: How to Gauge Pin Diameter, Tube Width, and Length
Never order replacement link pins by watch model name alone. Revision changes and aftermarket bracelets make physical caliper verification essential. Take three readings from your sample pin or link bore:
First, measure pin shank or tube outer diameter across the unthreaded center. Second, measure functional length under the screw head to the tip, or outer link span. Third, for threaded fasteners, measure head diameter and thread crest diameter.
What to measure | How to measure at the bench | Craft notes |
|---|---|---|
Pin or tube outer diameter | Digital caliper jaws across unthreaded center shank | Match within 0.05 mm; oversized pins bind, undersized pins rattle |
Overall length | Caliper depth probe or jaws from under head to tip | Pin must sit flush with link flanks without protruding |
Screw head diameter and depth | Caliper inner jaws across head; depth probe for height | Head must seat flush inside counterbore without binding |
Thread diameter and pitch | Caliper jaws across thread crests; compare thread pitch | Never force mismatched threads into female link tapping |
Tube collar outer diameter | Caliper jaws across central or end collar tube | Sits inside center link bore; pin presses through collar |
Freeing Seized Link Screws and Seating Threads Without Damage
Threaded link screws often seize from threadlocker, dried sweat, or corrosion. Forcing a seized screw slips the driver, burring slots and scratching links.
Verify tool fit first. Select a hollow-ground screwdriver blade that fills the slot without wobble; match your driver using our watchmaker screwdriver blade size guide. If the screw remains tight, apply penetrating solvent or alcohol to the seam to soften threadlocker. Bench hands touch a heated soldering iron tip to the screw head for several seconds to break the bond; heat is a last resort and must never be applied near leather straps, rubber gaskets, or plastic parts.
To seat a screw pin without cross-threading, place it in the bore, rotate backward until you feel a tactile click as threads drop, then thread forward finger-tight before a final snug turn.
Catalog Link Pin Assortments Compared
The table below summarizes the fastener families, stated dimensions, and refill quantities available across our catalog assortments. Use these specifications to match your caliper measurements to the correct bench refill.
Product | Stated sizes | Stated diameter | Count | Product link |
|---|---|---|---|---|
Screw Tube Rods (SP00002314) | 10.5 mm to 26 mm (10 sizes) | 1.0 mm to 1.4 mm tube; 1.2 mm to 1.7 mm head | 50 pcs | |
12-Size Screw Tube Rods (BDLS-RH-S-0001) | 8.5 mm to 19 mm stated spans | 0.85 mm to 1.8 mm stated diameters | 60 pcs | |
Cotter Link Pin Assortment | 5 mm to 24 mm (20 sizes) | Approx. 1.0 mm cotter head | 400 pcs (stated) | |
Screw Link Pins Set | 10.5 mm to 26 mm (10 sizes) | 1.0 mm to 1.4 mm tube; 1.2 mm to 1.7 mm head | 50 pcs | |
Rivet-End Screw Pins (Silver / Rose Gold) | 20 mm to 28 mm (5 lengths) | 1.3 mm tube; 3.0 mm and 3.5 mm head | 40 pcs | |
Rivet-End Screw Pins (Black / Gold) | 20 mm to 28 mm (5 lengths) | 2.1 mm and 3.0 mm tube; 3.5 mm and 4.0 mm head | Confirm by message | |
Pin and Tube Set (SP0003457) | 10 mm to 28 mm (10 sizes) | Φ0.9 mm pin; Φ1.2 mm x 5.9 mm tube | 150 pcs | |
Lug Stem Screw-In Rods | 12 mm to 30 mm (10 sizes) | 1.5 mm tube; 3.5 mm head | 60 pcs | |
Tube Friction Pins & Rivet Ends | 8 mm to 26 mm (10 sizes) | 1.0 mm tube; approx. 1.5 mm rivet head | Approx. 100 pcs | |
316 Steel Screw Pins (Rolex-Style Listed) | 8.6 mm to 19.4 mm (S1 to S18) | 0.80 mm to 1.4 mm thread; 0.95 mm to 1.7 mm width | 90 pcs |
Identify Your Link Pin and Request Catalog Verification
Before submitting a parts request, build a fastener identifier string from your bench measurements:
- Fastener type (cotter split pin, pin and tube, screw tube rod, or solid screw pin)
- Shank or tube outer diameter in millimeters
- Overall functional length in millimeters (plus head diameter or thread size if threaded)
Examples:
Screw Pin, 1.2 mm Ø x 15.5 mm L, 1.7 mm slotted head or Cotter Pin, 1.0 mm head Ø x 18.0 mm L.Kocandy is not affiliated with, authorised by, or an official dealer for Rolex, Seiko, Omega, Citizen, Breitling, Panerai, Hublot, ETA, Bergeon, Horotec, Vetus, or any other watch brand. All brand references indicate design compatibility or catalog stated-for designations only.
If your measured length, tube diameter, or thread pitch is not listed above, do not force an approximate fastener into your bracelet. Contact our bench team through our contact form with your caliper readings and link photos. We reply within one working day, and if your size is not listed above, send your readings anyway—we will check our extended warehouse catalog for an exact match.
