This is an optional Team Associated TC7.1 Brass Outer Arm Mount Set. These Outer TC7.1 FT Brass Arm Mounts replace the stock machined aluminum mounts (ASC31618) with a machined brass version for increased mass. Each mount is 7 grams heavier than the aluminum version.
A combination of these mounts, or completely replacing the stock mounts, helps with tuning the overall center of mass. Sold in pairs. The additional weight of the mounts is laser-etched.