Interface head piece worn by those operating sensitive technology. The H.U.D. allows a user the ability to keep one eye focused on the small headpiece monitor and, at the same time, maintain one eye on ship piloting controls or other external visuals, such as manning the flight operations of a Tel'tak.
The Serpent's Venom - Jacob/Selmak uses a H.U.D. to keep a ringed-in Tobin mine centered in the cargo hold of a tel'tak while avoiding other mines outside the ship.
New Order, Part 1 - Teal'c uses a H.U.D. while with Major Samantha Carter in one of the Asgard galaxies.