From The Stargate Omnipedia
Small handheld communicator, wrist-wearable, used by Genii
and their allies. A large power pack can be attached to the back, which may also amplify the signal to reach ally-connected relay stations, such as those used by the Manarians
Underground - The Genii use communicators to keep everyone informed regarding the presence of Sheppard's team.
The Storm - Kolya and his men use communicators to stay in touch as they search the city for hidden officers.
The Eye - Sheppard attaches a Genii communicator to his vest to keep up with Kolya's orders, and to communicate with the Commander himself.