The device is very small and is worn around the wearer's finger, much like an ordinary ring. Thus it can be easily concealed, making it an ideal weapon for a brainwashed Za'tarc. Once put on, it shrinks slightly to make it less noticeable. After activation the device extends a bit and then can be used to fire a laser-like red energy beam which is powerful enough to blast through a persons body and has considerable recoil. A secondary effect of the weapon is its self-destruct sequence which can be triggered by pressing a small blue button on the weapon. After a few seconds the device explodes, completely destroying the wearer.
The device became first known to Stargate Command during a meeting with the Tok'ra. There Major Thomas Graham pulls out such a device to kill the Supreme High Councilor Per'sus of the Tok'ra but fails and subsequently kills himself. Another such device is later used by Martouf to kill the President of the United States but he is also stopped. (SG1: "Divide and Conquer")
The last known user of the device (the same apparent version used by Osiris) was a Female Assassin who attacked Daniel Jackson after a bounty had been placed on the team by Netan, leader of the Lucian Alliance. (SG1: "Bounty")