DESC: Converts select M-Rock bags into convenient roller bagsProduct Material: Plastic and MetalProduct Weight: 4 lbs.This sturdy and tough 698 trolley is modular and securely attaches behind and belowM-rock products 662d, 663, 664, 670, 671 & 673 converting them into convenient roller bags. The telescope handle has half and fully extended lockable positions. The handle slides into the loops behind the compatible m-rock bags and velcro connecting straps below the bags securely hold the trolleys bottom section. Once the trolley is removed it collapses into a smaller, easy to store size in your closet, trunk or overhead bin.