This is a Streamlight Flashlight known as the ProTac, model 88073.
The ProTac 1L-1AA is a perfect everyday carry light. This dual fuel ultra-compact flashlight accepts a single lithium or alkaline battery" providing you with ultimate flexibility in the field.
Features:
Multi-function push-button switch
High, low, and strobe settings
Aluminum construction
Uses 1 CR123A battery or one AA
