This fits a one-piece toilet as a replacement cartridge to operate the system when the stem breaks. Have 4 Flushmate toilets and have replaced 2 with these kits. Plumber was able to remove the old system with put special tool but had to improvise. New system works good. Hope I get a thousand flushes!

This replacement product worked well and was easy to install.

Tech support was great, product installed easily and worked as stated. Sales team took a while to get back to me (room for improvement).

My old 501A from 1996 was on its last legs and Bobby in Tech Support told me that alas it was time to replace the unit. He walked me through the details, gave me the part numbers, answered all my questions about compatibility. He was very knowledgeable, friendly and patient with my questions. I received the replacement unit yesterday and this morning set about installing it. The instructions were all perfectly clear and everything was going well until I hit a snag on the tank-to-bowl gasket. The new gasket appeared too large and incompatible with the old. So I called Tech Support again and spoke with Martin, who reassured me it was normal — a universal gasket that compresses — and walked me through how to reattach the tank. Ten minutes later the job was completed with no "New System Adjustments" required. Their Tech Support department is top notch. Five stars.

a very good product and good service