This is for a pack of 10- RED -Submersible Underwater Lights all with batteries included- Just twist the light. It is an easy on/off switch with replaceable batteries. The battery included gives the lights 12-16 hours of operation. These are not returnable. The batteries for these are CR2032-and 1 is used in each light. The size of these lights are 1" tall and 1 1/4" across. These lights can be used for Parties in arrangements or put in a Pool of water, fish tanks, anywhere you want to light up.