Replacement 20mm Curved FKM Rubber Strap for Omega Seamaster 300

Product Overview

Fuerman makes custom fluororubber material watch straps for specific dive-watch references, and this two-piece band is shaped for the Omega Seamaster Diver 300M. Its 20 mm lug width is the standard measurement used across the Seamaster 300 and Planet Ocean families, so the band seats on the case instead of floating above it, and the buckle end narrows to 18 mm for a tapered line on the wrist. Quick-release spring bars come already fitted, which turns a strap change into a by-hand job that takes seconds and needs no tools. This is an aftermarket replacement part rather than a genuine Omega product, but it is made to the same 20 mm lug specification, so the original clasp, the spring-bar positions and the case curvature all still line up. Most owners come to it for one of three reasons: the original rubber has gone hard, shiny or torn at the buckle; they want a band they can swim in without thinking about it; or they want a colour that sits better with the dial than plain black.

Curved Ends & Case Fit

• Moulded to the case profile. The ends are curved to follow the Seamaster 300 case, so the band meets the lugs flush instead of standing away from them.
• No gap, no lifted edge. A straight-end band leaves a shadow line and a lifted corner at the lug; the curved ends close that gap and give the watch an integrated look that matches the case finish.
• Softened lug edges. The moulding at the ends is micro-arched, so the band does not catch or scratch a shirt cuff as your wrist moves through the day.
• Right from the first wear. Because the curve follows the case rather than being forced into it, the band sits naturally on the wrist straight away, with no break-in period where the strap fights the watch.
• Shaped for this reference, not trimmed to fit. The curve is why a custom fluororubber material watch strap built for the Seamaster looks right from the side as well as from above, where a general-purpose 20 mm band can still show a gap.

FKM Fluororubber Build

FKM fluoroelastomer is the family of rubber used for seals in aerospace and automotive engineering, and it earns its place there for the same reason it suits a dive watch: heat, oils, chemicals, salt water and strong sunlight do not easily change it. On the wrist that means a band that shrugs off sweat and seawater, keeps its colour in the sun, and stays soft instead of going hard, shiny or brittle the way natural rubber can after a season of wear. Custom fluororubber material watch straps are also the gentler option for sensitive skin. The surface is hypoallergenic, anti-dust and non-sticky, so it does not grab lint from a sleeve or leave a tacky film on the wrist. The band is fully waterproof and dries in moments after a swim, which is why it works as well at a desk as it does on a boat. Softness is there from the first wear, with no stiff break-in period, and the material keeps that suppleness over time rather than stiffening with age.

Specifications

Sizing & Wrist Fit

• Two-piece coverage. The band is supplied as a 120 mm piece and an 80 mm piece, which together cover wrists from roughly 14 cm to 21.5 cm (about 5.5 in to 8.5 in).
• Check the lug width first. Measure the gap between the spring-bar holes on your watch, or check the reference: the Seamaster Diver 300M 42 mm, and the Seamaster 300 and Planet Ocean references that take a 20 mm band, all suit this strap.
• A tapered line. 20 mm at the lugs down to 18 mm at the buckle keeps the profile slim, and 18 mm is the width your original clasp expects.
• Tail management. Two rubber keepers are included, so a long tail stays folded flat instead of flapping loose on a smaller wrist.
• Buying a watch strap online starts with two numbers. The lug width tells you whether a band will fit, and your wrist measurement tells you whether the length is right. Both are easy to check with a ruler before you order.
• At the top of the range. If your wrist measures more than about 21.5 cm, or you wear the watch loose over a wetsuit sleeve, tell us before ordering so the length can be checked.

Fitting the Strap

1. Work on a steady table over a soft cloth, so a dropped spring bar or a slipped hand cannot mark the case.
2. Press the small lever on one pre-fitted quick-release spring bar and hold it while you slot the curved end between the lugs.
3. Release the lever and let the bar settle into both lug holes, checking that it sits squarely before you move on.
4. Fit the second piece on the other side of the case, keeping the band aligned with the case edges as it goes in.
5. Pull the band gently away from the case in both directions to confirm each bar is fully home.
6. Thread the tail through the keepers and your clasp, then adjust so the buckle sits centred underneath the wrist.
7. The bars come fitted, so there is nothing to assemble; if you also own flat-end straps, keep a spring bar tool and spare bars with your kit for those.

Dive, Sweat & Everyday Wear

A dive watch leads a mixed life, and this is a fluororubber material watch strap built for the whole of it rather than for one setting. In the water the curved ends keep the band tight against the case, with nothing to catch when you pull a wetsuit sleeve over it, and the surface sheds water instead of holding it, so the band is dry again a few minutes later. On hot days it stays cool against the skin, with no tacky film, no dust clinging to the surface and no need to take the watch off to wash your hands. At a desk it reads quietly, with the matte finish and the slimmer buckle end keeping it looking like part of the watch rather than an add-on. Packing for a trip is where the quick-release bars pay off: if you carry a second colour, changing over takes seconds in a hotel room and needs no tool kit. One practical note for divers — the strap itself is waterproof, but your watch's water resistance depends on its seals and service history, so have the case checked before a serious dive.

Colour Options

• Black — the safe default: it disappears against a black bezel and dial and works with everything else in a wardrobe.
• Blue — ties in with a blue dial and bezel for a single-tone look that reads deliberate rather than loud.
• Army green — a muted, outdoorsy tone that suits a steel case in casual settings.
• Orange — the classic dive-watch accent, and the brightest way to lift an otherwise plain case.
• White — crisp against steel and dark dials, and the most visible of the five in daylight.

Ordering & Delivery

1. Set the size to 20 mm. That figure is the lug width, the distance between the spring-bar holes, not the buckle width.
2. Choose your colour; all five share the same FKM build, curved ends and pre-fitted quick-release bars.
3. Decide about the buckle. The band is made to work with your original Omega deployant clasp and with aftermarket buckles, so confirm with us if you need a buckle supplied with the order.
4. Buying a watch strap online is simpler when you check two things first: the delivery time to your country and the return and exchange window that applies to your order. Confirm both before you place it if timing or fit is critical.
5. If you like to rotate colours, order both at once rather than in two rounds.
6. Keep the original strap and clasp somewhere safe. They are useful if the watch is ever sold or sent in for service.

More Straps in the Range

Care & Maintenance

Looking after a fluororubber material watch strap comes down to one habit: rinse it. After a swim, a shower or a long hot day, hold the band under fresh water and wipe it dry with a soft cloth. FKM does not absorb water, so nothing soaks in, no sticky film forms and the strap is ready to wear again within minutes. Salt water and chlorinated pool water are the two things worth rinsing off promptly, and the rinse should reach the area around the lugs, where sand and dried salt tend to gather around the quick-release bars. When marks appear. A little mild hand soap on a damp cloth lifts everyday grime, sunscreen and skin oils. Skip alcohol, solvent cleaners, nail-polish remover and abrasive pads — they are not needed on a non-stick surface and can dull the matte finish. Rinse the soap off with clean water and pat the band dry rather than rubbing it. Taking it off and keeping it. Release the band by pressing the lever on each pre-fitted spring bar instead of easing it out with a fingernail or a blade, so the lugs and the bar seats stay unmarked. A spare strap stores neatly lying flat, out of direct sunlight and away from sharp tools, metal buckles and loose keys in a drawer; a small cloth pouch is plenty. If you rotate colours, keep the original strap and clasp in the same safe place — they are worth having if the watch is ever sold or sent in for service. Habits that age a strap early. Pulling the watch off by the tail, fastening the clasp so tightly that the rubber stays stretched, leaving the band for weeks on a sunny windowsill or in a hot car, and letting sunscreen or insect repellent sit on the rubber are the usual culprits. Check from time to time that both spring bars are fully seated and that the keepers still hold the tail flat, and if a bar ever feels loose, replace it before the next swim. The band itself is waterproof; your watch's water resistance depends on its case seals, so keep up the service schedule as well.

Technical Support & Model Matching

FUERMAN has been supplying watch parts and accessories from Huadu District, Guangzhou since 2010 — 15+ years in the trade, a 60-strong team and a deep ready stock held in China. Our technical team, which includes technicians with 30+ years of watchmaking experience, matches items to your watch by brand, model or reference number before you order, so you know it will fit. Send a photo or a measurement if you are unsure: we will confirm the right choice, talk you through fitting, and stay with you afterwards — troubleshooting, replacement parts and after-sales help long after your order arrives.

FAQ