From The Stargate Omnipedia
Ancient space suit
EVA suits of Ancient
design, allowing the wearer to traverse environments not suitable for human life.
The suits are equipped with voice-activated radios for communication between suit wearers, as well as a separate toggle for connecting to a ship's communication systems. The left arm includes an slot for an Ancient remote.
The Ancient exploratory vessel Destiny was equipped with numerous suits, but most have degraded after countless eons of dormancy. Apart from the helmet, the suit design is remarkably similar to the environmental suits used by a group of rogue Asgard in the Pegasus Galaxy -- leading to speculation that they may have taken the design from the Ancients long ago, or perhaps even had access to Destiny at some point.
Water - Destiny scientists complete repairs on two Ancient suits, just in time for Col. Young and Lt. Scott to use them to retrieve supplies of water from an alien world.
Earth - Dr. Brody and Sgt. Riley use the suits to effect repairs to Destiny's power conduits, but a rupture leaves Riley critically injured.
Divided - Young and Scott use the space suits to circumvent doors locked down by Dr. Rush and the civilians.
Sabotage - Lt. Scott dons a space suit to deliver a repair robot to Destiny's F.T.L. drive.
Incursion, Part 2 - Lt. Scott and Sgt. Greer use the suits for a talk on Destiny's outer hull, setting the shields to protect only the exposed part of the ship from pulsar radiation.