Pre-drilled plate to fit Porter-Cable 690 and 890 series and the Bosch 1617. Level-Loc rings mount flush with plate surface. Removable brass starting pin. Reducing rings that installs in seconds and locks in place flush every time. Makes set up changes simple by allowing you to quickly swap inserts. Three rings are included to allow the use of large or small bits, as well as guide bushings: 1 in , 1-3/16 in (for use with Porter-Cable style guide bushings) and 2-5/8 in Plate measures 9-1/4 in x 11-3/4 in and is madefrom 3/8 in thick phenolic that won't sag, even under the weight of heavy routers. The plate comes with plate mounting screws and detailed installation instructions.