The RAP-B-397-1-201U consists of the RAM Tough-Clamp™ clamping base and 1" ball compatible STANDARD length double socket arm. The RAM Tough-Clamp™ includes a 1" ball which can be used to mount a variety of products utilizing RAM's vast selection of mounting solutions. Attach your GoPro Camera, Smartphone, RAM AQUA BOX® Pro or similar light weight device on almost any flat surfaces and square rails. Clamping Dimensions:1. Flat surfaces and square rails from 0" to 1" thick2. Round rails from 0.25" to 0.75" OD