Brand: Racetech Gauges
This special copper washer is used to seal between the female 3/8 BSP gland nut and the male-male adapter on most Racetech and Smiths mechanical temperature gauges. The ID is sized to slip over the 10mm sensing bulb, and the 15mm OD fits neatly inside the female nut. Sold individually.
Note: All of the Racetech temperature gauges that we carry use this size, but some similar British gauges use a 12mm ID sealing washer. Both washers have the same 15mm OD, so you can ream this 10mm washer out to 12mm if needed.