Shower Door Rollers Description: Set of 4 grooved wheels and screws provided. 100% new and high quality. Multi-functional small rollers suitable for many different makes. Wheels are internally threaded. Specifications: A - Wheel diameter: 19mm. B - Wheel thickness: 5.5mm. C - Protruding boss diameter: 8mm. D - Protruding boss height: 5.5mm. E - Hole diameter: 3.4mm.