YuanQian Set of 4Twin Shower DoorRollers (2pcs top and 2pcs bottom) Suitable for most Shower Enclosures Shower Cabins and Steam Cabin Enclosures Easy Glide Eeplacement Shower Door Roller From Picture Clearly see which Top /Bottom Roller Glass Open-Hole: 8-13MM can be fit GlassThickness: 4-6mm Suitable for most Shower Enclosures Shower Cabins and Steam Cabin Enclosures 2Double Top +2 Double Bottom 25mm.