Sia 1950 Siaspeed 9 inch drywall sanding disc built for drywall, wood & paint prep. Very High stock removal rates and excellent finish.  It is a performance enhancing open coat grit mix with ceramic aluminum oxide in the 80 grit.  The 100 grit through 220 grit is a semi-friable aluminum oxide and blue fire mix.  This Sia option has 128 holes and is the answer for the Festool Planex and other compatible sanders.  It's available in 80 grit through 220 grit for intermediate and fine sanding. It is packaged 25 discs per box.