Tollan health implant
From The Stargate Omnipedia
Subcutaneous implant worn by all Tollan, monitored by Tollan computers, health officials and the Curia. The implant is often installed in the underside of the wrist and can be accessed with a health monitor, detailing health conditions. If an individual goes critical the implant sends out an emergency distress call, bringing in help in less than five minutes.
Tollan health implants can be removed without alerting the Curia.
KEY EPISODE
Between Two Fires - Narim explains the purpose of the health implant to SG-1, and later gives it to Carter and Daniel as he hides from his people in an attempt to save them from themselves.