This versatile subbase is pre-drilled to fit Sears, Ryobi, Makita, Hitachi, DeWalt 625/621, Freud FT2000E and Elu 177 routers. Its 1.2" center opening is rabbeted to accommodate the mounting flange of Porter-Cable style universal template guides. It's a good way to enable your router to use template guides without totally obscuring the work; the 3/8" plastic base plate is clear as glass, so (depending on your router's base design) you'll be able to see dovetail jig guide fingers and other templates through the router base rather than putting yourself in harm's way for a look underneath the machine.