20":640pcs, 40":1290pcs. .Maintains same constant cleaning power 60-minute rechargeable Ni-Cd battery Picks up fine debris and pet hair Cleans wood, slate, tile and low to medium pile carpet. Travels through several cleaning Three timer settings runs from 20 to 60 minutes, allows users to select how long they want to cleanpatterns to ensure the entire room is clean. Uses infrared for sweeper prevents AutoSweeper from falling down stairs . Designed with light sensor AutoSweeper, cleans even under sofa or bed. Designed with nonstick hair brushes. Cleaning route includs 5 different patterns, Special bounce, Spiral, Along the wall , Polygonal spiral and S shape. with Auto Rechargeable device:when the Vacuum Cleaner battery power is not enough, The Vacuum Cleaner will auto look for the Auto Rechargeable device and Auto Rechargeable battery then auto working. mininum order qty 500pcs.