Set of 4 Twin/double Butterfly Shower Door Rollers (2 top & 2 bottom rollers) Luxurious TOP QUALITY product These rollers fit glass shower doors with 2 glass holes 26mm apart. Minimum hole size is 8mm. Top rollers are adjustable up and down to allow the door to be lined up to mate with the frame or magnetic seal where you have a pair of doors. Bottom rollers are spring loaded. Swivel action to also fit curved and quadrant showers. Diameter of wheels: 25mm Width of wheels: 6mm Finish: chrome Materials: Chromed plastic body, 304 stainless steel micro-bearings, nylon wheels, zinc alloy axis - never rust.