1.Roller material: solid zinc alloy material with plastic cover 2.Roller wheel diameter: 23mm 3.Roller wheel thickness: 5mm 4.To fit maximum glass thickness: 4-8mm 5.To fit Minimum Hole size in the glass: 10mm 6.Each roller has equipped with one chrome plastic cover. 7.The current roller design loaded with spring is also fit curved showers doors. 8.DIY Replacement: The rollers replacement can be easily replaced by yourself and you can simply disassemble it by screwdriver and replace with new rollers on glass doors. 9.Product Features: The 4pcs of shower door rollers provided by KEABATH is made in good material and better quality to make it much longer life time. It can control the movement of each rollers together with glass by smooth running of the door movement forward and back.