The NR-1800 features a simple push button to turn on\off and cycle through brightness levels. Built in bottle opener on the rear of the light make getting to those refreshments after the dive day a breeze! Included carry case lets you pack the light, battery, and charging cable all in a small kit to fit easily in your dive bag. Battery level indicator built in to button shows if you have a full charge quickly before you get in the water. The new 21700 battery is now using USB C technology so no more upside down cables, just plug directly in to charge!