The B size 1'' ball double socket arm made of 6061-T6 aluminum alloy material with CNC machining and iii grade hard anodized surface for durability and reliability in the most demanding environments Medium Arm: with an overall length of 3.54" Compatible with RAM Mounts & BRCOVAN any B size 1'' ball components, including mounting bases and device holders Suitable for other 1" ball device mounts, such as bike phone mounts, motorcycle phone holders, action camera mounts, navigation mounts, marine electronic mounts, etc.