I'm cleaning out a bunch of stuff and I haven't used these since getting a lathe so they need to go. The top mandrel is carbide and used to just touch up the top of the threads and integral lugs, the bottom mandrel is HSS and is a Gen II which will cut the integral lugs, tops of the threads and the face of the action in one shot. I found enough variance in the actions that sometimes I would just clean up the front receiver and not touch the lugs so this kit let's a guy take minimal cuts. Bushing set has been used more. These tools are $619 new looking to get $300, perfect for the DIY prefit guys!!