Adams 5" Machine Backing Plate was designed for use with the Porter Cable 7424XP Dual-Action Car Polisher. The flexible foam material is designed to work in perfect balance with your polisher and Adams Foam or Microfiber Polishing Pad System for smooth, safe operation. Compatible with the 5.5" Microfiber Cutting Pad or 6" Foam Pads the 5" backing plate maximizes the performance and polishing power of the Porter Cable and similar orbital polishers. NOTE: Compatible with any polisher that accepts a 5/16" threaded backing plate. Includes spacing washer for proper shroud gap on Porter Cable 7424xp and similar machines.