
Jack wearing HUD
The HUD headset was a device which could be used while flying a Tel'tak, increasing the number of ship's systems that a single pilot could effectively monitor.
The Tok'ra Selmak/Jacob Carter used a HUD headset when he and SG-1 (minus Teal'c) were in the Tobin system's minefield. He used this HUD to be able to see the position of the mine they had ringed into the back of the Tel'tak with one eye while using his other to look at the positions of the mines outside the ship.
Later when Major Samantha Carter asked for Selmak's help Colonel Jack O'Neill took over flying the ship and wearing the HUD. (SG1: "The Serpent's Venom")
The headset was seen again when Teal'c used it. This was when he and Carter used the Tel'tak O'Neill had upgraded using Ancient knowledge. (SG1: "New Order, Part 1")