Mimic camouflage device
From The Stargate Omnipedia
Device that allows a user to quickly impersonate a target by scanning his or her physical form and then duplicating it for the user. The technology can quickly replicate a false image that includes not only specific facial features but even the wardrobe of another individual.
The device is small and spherical in shape, though this scanner portion is probably also connected to some sort of wearable holographic projection.
KEY EPISODE
Bounty - In an attempt to capture Cameron Mitchell, a bounty hunter of Tenat's race takes on the façade of Phil in the hopes of getting close to the Colonel.