Clamping across the rear crossmember, the rear end squaring gauge has engraved measurements that go down to the 1/16 of an inch. As you can see from the pictures, the gauge is easy to clamp to the car. Best used with a laser that can be purchased from CRP for additional cost. Very easy to use, has been done at the track on raceday in under ten minutes and greatly helped the car for the rest of the day. Gauge sold by itself with instructions. Clamps and lasers available.