The main component is a motion sensor that goes inside the tank and triggers the flush cycle when it detects your hand. The four AA batteries that power it will last for a year.  Photo 1 of 5 in Inexpensive Touchless Flush Toilet Kit by Alexander George

Inexpensive Touchless Flush Toilet Kit

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The main component is a motion sensor that goes inside the tank and triggers the flush cycle when it detects your hand. The four AA batteries that power it will last for a year.