Lets you measure the brake pad friction material from through the alloy wheel spokes
This tool is ideal for measuring and putting a value on the friction material on car brakes, without, in the case of when that car has alloys, the need to remove the wheels.
Obviously a serious home DIYer car fixer can judge that from just looking, but if anyone want to keep an actual record on their car's brake pad wear, then this is a tool for doing that with.