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It is a countersunk screw with a rubber ring tucked under the head. Drive it in and the head ends up flush with the surface. Meanwhile, the rubber ring gets squished and seals the hole. Water and dust? They stay out.
Two reasons. First, looks. The head disappears into the material. No bumps sticking up. No edges to snag on things. Second, space. Flush mounting means nothing protrudes, so covers and wires slide right over.
The rubber ring sits in a groove cut into the underside of the head. As you tighten the screw, that ring gets pressed between the head and the surface. The more you turn, the tighter it seals. When fully seated, the rubber has filled the gap completely. Water cannot get past.
M2, M2.5, M3, M4, M5, and M6. Lengths from 4mm to 30mm. Custom sizes available if you need them.
PCB mounting. Instrument panels. Electronics enclosures. Marine gear. Control boxes. Anywhere you need a flush finish and a watertight seal.
We check every O ring before it goes out. Every batch is tested. ISO 9001 and ISO 10012 certified.
YH Fastener has been making screws and fasteners since 1998. We are based in Guangdong, China. Our product range includes flat head sealing screws, self tapping screws, machine screws, shoulder screws, and custom fasteners. We hold ISO 9001 and ISO 10012 certifications. Every batch is inspected before it leaves our factory. We sell direct and ship to over 60 countries worldwide. Got a custom requirement? Send us your drawing or sample. We are happy to make what you need.
Yes. It is countersunk. Sits level with the surface.
Yes. The hole has to be countersunk for the head to sit flush.
No. The O ring handles the sealing. No sealant required.
304 stainless works. 316 stainless is better near saltwater.
One meter of water for thirty minutes. No leaks.
Yes. The rubber springs back. Reuse them a few times.
