Graco 15A739 COVER, AIR, SST 1590 55 ton MARSHALLTOWN Blue Gliders are best 389 MARSHALLTOWN Blue Gliders are best used after floating your concrete surface to ensure a fast application and smooth finish over large areas Abrasive Material Zirconia Alumina Disc Type Type 27S Grit 40 Series ENDURO FLEX Item Flap Disc Operating Speed (RPM) 10200 RPM Abrasive Type Coated Abrasive Grade Coarse Abrasive Grit 40 P40 Flap Disc Type Type 27 Features Trimmable Backing Plate Material Plastic Maximum Operating Speed 10 with two units required per air motor configuration T 23 in the parts diagram) is a genuine Graco replacement for the 1590 model