The Tollan detachment device is worn on the chest and cannot be removed. It suppresses a Goa'uld's ability to silence the host, allowing each to speak at will. The color indicates who is speaking, by displaying a red light for the symbiote, and blue for the host. While on Tollana and throughout the triad to decide his fate, Klorel wore a detachment device, allowing Skaara to speak.
Episode Reference: Pretense