Tok'ra bio-sensor
From The Stargate Omnipedia
A circular device worn on the chest which monitors the body functions of a specific individual. Developed by the Tok'ra, the sensor is capable of working on humans, and can transmit data over significant distances. The information is processed into readable data on a Tok'ra data pad.
KEY EPISODE
Upgrades - The Tok'ra anise arrives with Antoniek armbands as well as Tok'ra bio-sensors to monitor the test subjects for the alien devices.