This tool is used to aide in accurately measuring the closer shims on any 2 valve Ducati [8mm valves].
Set it inside the shim and measure the entire stack, then subtract 1cm to get the thickness of your shim. If you don't have a micrometer and do have a set of vernier calipers then you must have this tool for the job. 2 tools are shown so you can see the tool, only 1 tool is required for the job and is included by ordering "1".
The 2nd detail picture shows a 7.30 shim with this tool sitting in place, and our vernier calipers taking the measurment correctly. A 7.30 shim with tool give you a 17.30mm measurment.