Avid, a subsidiary of Sram Corporation, manufacture brake components for the cycling market.

Products include the popular BB7 and the budget BB5

Both brakes are becoming more and more popular in the Trials market because of their ease of adjustability and low maintenance. The BB7 is superior to the BB5 because of it's extra adjustor, meaning you can adjust both sides of the pads in the caliper. The BB5 has only one adjustor on the stationary fixed pad side of the caliper, if you need to adjust the moving pad you would have to adjust it by moving the brake cable. See: How to fit an Avid mechanical disk brake - Video Tutorial

They come in 160mm, 185mm and 203mm rotor sizes. Adapters are supplied for each rotor size and can be found on Chain Reaction Cycles.