| Main centres: | 1-3 business days |
| Regional areas: | 3-4 business days |
| Remote areas: | 3-5 business days |
Watch Case Back O-Ring Gasket 0.6mm Bold Pack 36 To 40mm
Large watches take a beating, and their gaskets need to keep up. The Bold Pack is a 15-piece O-ring case back gasket assortment covering five large case sizes, 36mm, 37mm, 38mm, 39mm, and 40mm. With 3 gaskets per size at a precise 0.6mm thickness. It is built specifically for modern sport watches, dive watches, and the oversized everyday wearers that dominate today's watch market.
Watches in this size range are worn hard. They go swimming, get sweated on at the gym, and face daily exposure to water and humidity. As a result, their case back gaskets wear out faster than those on dress or vintage pieces. A gasket that looks intact can still fail under water pressure, especially once it has been compressed repeatedly over months of use.
Replacing the gasket regularly is the single most effective way to maintain water resistance in a sport or dive watch. Fortunately, The O-Ring Gasket 0.6mm Bold Pack makes that easy. Select the matching size, apply silicone grease, seat it in the groove, and close the case back. The entire job takes less than five minutes and costs a fraction of what water damage repairs would.
Specification
Three gaskets per size means you have enough for multiple services before needing to restock, making The Bold Pack one of the most cost-effective maintenance purchases for any sport watch owner or repairer.

Measurement Guide
If you still have the old O-ring, even if it is stretched or broken, you can use it as a reference. Measure the Thickness, Use a digital caliper to measure the "cross-section" (thickness) of the rubber. Measure the Internal Diameter (ID): Lay the gasket flat on a surface without stretching it. Measure across the inside of the circle from one inner edge to the other.
If the watch is missing its O-ring entirely, you must measure the watch case itself to find the correct fit. Measure the Case Groove, locate the circular track (groove) where the gasket sits inside the watch case. Use a digital caliper to measure the Inside Diameter of that groove.
Order The Watch Case Back O-Ring Gasket 0.6mm Bold Pack today and make sure your sport watches stay sealed, protected, and ready for anything