The 1/2" Shaker stile and rail cutters cut a perfect 7/32" slot which creates a perfect fit for today's 1/4" undersized plywood-no more loose-fitting panels.Stile and rail cutters have a 7/16" engagement. There is an optional 1/4" groove cutter (SM82442BL-2 sold seperately) that can be interchanged with the cope cutter for regular 1/4" thick plywood. Important: You will also have to shim the pattern cutting bit and raised panel bit with a 1/32" shim making them 1/4" to allow for perfect fit.