Gun Runners - can be bought from the Vendortron.
It provides a damage threshold of 17 (same as combat armor, reinforced) as well as a bonus of +5 to Sneak and can be repaired with other suits of recon armor, Stealth suit Mk II, NCR trooper armor or any combat armor with the Jury Rigging perk. This armor is identical in appearance to the recon armor available in Fallout 3, though with a much higher value. Unlike the under armor for the T-51b power armor models, this one is also designed to offer limited protection from anti-personnel weapons. Its purpose is twofold: it allows the user to actually operate the armor and protect soft tissue from moving parts inside the suit and heat.
Attached to it is the interface and mounts for the T-45d power armor. Intended to serve as the under-armor of the T-45d power armor, the recon armor is a vacuum-sealed asbestos jumpsuit covering the entire body.