SIMs beacon

A SIMs beacon was a flashlight-like device that was worn like a wrist band, often used by away teams in dark areas.

SIMs beacons were the improved successor to the palm beacons, leaving the user's hands free for other tasks.

In 2376, Tuvok was in a phaser fight with his impersonator, Mobar, he used the opportunity afforded him when Mobar was admiring him to shine his SIMs beacon in his eyes and stun him. 

In 2377, Crewman Yosa was attempting to fix a power fluctuation in a Jefferies tube when someone that had been attacking former-Maquis (later found to be Tuvok under mind control) blinded him in a Jefferies tube before he could escape, and put him in a coma. 

In an alternate timeline where Voyager'' was destroyed and frozen on a planet in the Takara sector, Harry Kim and Chakotay were equipped with a future configuration of the SIMs beacon, no longer using an elastic-strap, but a solid rectangular band around the arm. Instead of two light sources, it had a single larger and more sleek one.''

Background
The SIMs beacons were named after their real-life prop creator Alan Sims. He describes how to build one from simple parts "available at your local 7/11" in his book Star Trek: Aliens & Artifacts.

The flashlight portion of the beacon, as shown in the It's A Wrap! sale and auction, is made up of a Sure Fire light.