18650 to 21700 battery Adapter The 18650 to 21700 battery adapter by Sniper Hog Lights is designed to allow users to use a smaller 18650 battery in devices that typically require the larger 21700 battery. This battery adapter will allow you to use a 18650 battery in lights that use 21700 protected battery. Simply slide the 18650 battery into the adapter and then insert into light. This adapter will work in any o