The 106-AC installs onto the upright tube of select Park Tool portable repair stands to accommodate the #106 Work Tray or PTH-1 Paper Towel HolderFits the following Park Tool repair stands directly: PCS-1 (2001-2004), PCS-4 (2001-2003), PCS-4-1, PCS-4-2, PCS-9Pre-2001 PCS-1 and PCS-4 stands require use of PCS-EXT Extension to be compatibleTray Adapter106ACUPC/EAN/GTIN: 763477012227