Includes (1) 877757 Lock Nut. New, Bulk Packed. Genuine OEM replacement part. Consult owners manual for proper part number identification and proper installation. Compatible with: Porter Cable : 7800 Type 1 Drywall Sander, 7800 Type 2 Drywall Sander, 7801 Drywall Sander, 259385 Type 2 Drywall-Sander, 259485 Type 1 110V Drywall-Sander, 7800 Type 3 Drywall Sander 3.5 Amp