Quantity: 8pcs shower door rollers. (Please note the screw of the shower door roller is M6*12mm. Please measure the screw size you need for your shower door before ordering in case itwould not be compatible with your shower door.)Dimensions: Wheel Diameter: 20mm/0.78inch; wheel thickness: 5.5mm/0.21inch; Inner Hole: 5mm/0.19inch; Screw specification: M6; Screw Length: 12mm/0.47in; Wheel steel part: 11mm/0.43in in diameter,5mm/0.19in in height.Material: Nylon wheel + copper chuck. The products are more durable and last longer.Design: Easy to install reel, waterproof nylon material, the screws are made of stainless steel, it is strong and durable.Wide application: suitable for sliding glass doors in shower rooms and steam rooms.