This is the Tray Base Mount from Panavise.

FEATURES: Works with the #300 Standard Base, #305 Low Profile Base and the
            #201 Panavise Junior Combo
          8.5" (218mm) diameter base and non-slip neoprene feet
          Three pre-drilled, tapped 1/4-20 holes on outer edges to attach
            accessories
          Six recessed areas to keep parts and tools organized

INCLUDES: Tray Base Mount from Panavise

SPECS:    Outer Diameter: 8.5" (218mm)
          Parts Well Depth: 0.370" (9.4mm)
          Inner Bolt Circle Diameter: 4.3125" (109.5mm)
          Outer Bolt Circle Diameter: 7.875" (200mm)
          Weight: 1lb 14oz (0.8kg)

                                                                   jxs 12/17/10
                                                                         ir/jxs