100* counter sinks are typically used for cars that use 8-32 screws to bolt the front end on...and not all of them use 100* so you have to be sure you have the right one. CRC cars prior to the Xti used a 100* counter sink for the front end but no longer do. AE cars used to as well but they've gone all metric and to smaller screws on the front end. The only car I can think of that might still use them are the Speed Merchant cars.