Size: suitable for 2.3 Inch (2.16in /58 mm) tank hole. Dual flush function. Compatible with TOTO, American Standard, KOHLER, Twfords, Armitage Shanks, Geberit, Siamp, Wirquin, Cookr & Lewis. High quality: The toilet button spring is made of high quality 304 stainless steel wire, which is durable and elastic. Instructions: 1. Unscrew the lock nut and insert the button into the hole. (Full row buttons and half row buttons need to be consistent) 2. Check whether the button rod is just in contact with the button. If it is too long, you can cut it short. If it is too short, you can turn the button rod out to adjust the required length, and screw in the lock nut until it is firm. Useful: Using the high-end plating technology, multi-layer plating process, high brightness and ultra-smooth surface, long-lasting. Note: Please check the size of your toilet lid hole before you buy, and our toilet button can compatiable with most dual flush toilet with 58mm hole in the cistern lid.