This innovative light has no buttons; its internal sensor responds to the touch of your thumb. A swipe to the left turns on the light, additional swipes change the setting, and a swipe to the right turns it off.
It has a 16-lumen high setting that's surprisingly bright for a key-ring light, a battery-saving low setting, and an attention-getting blink setting. You can also dim the light to any point between the high and low settings.
It runs for up to 9 hours at maximum brightness or up to 64 hours at minimum brightness, and uses two included lithium CR2032 3V batteries.
An S-Biner™ clip lets you conveniently attach it to a key-ring or zipper pull.