The Models 504/505 are orbital sanders with a 3/32" offset. The smaller rectangular orbit allows better sanding access for bumpers, recessed areas, and new panel prep. Both sanders use standard 2 3/4" velcro sandpaper rolls. Velcro pads securely hold scuff pads for easy new-panel prep. Built-in pad release feature. Models 504 2 ¾" x 4" Velcro Pad Models 505 2 ¾" x 5 ½" Velcro Pad.