Package Content: Set of 4 double shower door rollers (2pcs top and 2pcs bottom). (recommended for 14mm glass hole) Galvanized Door Rollers: Shower door double rollers top and bottom 23mm (diameter), plated surface, rust-proof; Suitable for glass door thickness 4-6mm, open glass hole 12-14mm. These replacement shower door wheels are suitable for most shower enclosures, shower stalls and steam rooms, installed at the top and bottom of the shower door for easy opening and closing (not fit for hole diameter less than 12mm) No noise when opening the shower door and these glass shower door rollers ensure smooth sliding. It is easy to install and maintain. (recommended for 14mm glass holes). It is recommended to replace the shower door rollers with plastic shell every six months, and it is recommended to replace the metal shell pulley every year.