While it isn't mentioned in the description, this BA-22 parachute was used by NASA's Johnson Space Center. I've already bought two of these from the same seller and the provenance is in the maintenance log.
The parachute is still loaded (the drogue chute is spring-loaded inside and will shoot out if the rip cord pins are removed) and the MD-1 emergency oxygen bottle is still full (it will be activated if you pull the "green apple," which is a green wooden ball), so do handle them with caution. The automatic opener (red knob) usually activates via a pyrotechnic charge although these were removed before the parachutes were disposed of.
I'd advise not attempting to unload the pack without the help of a professional parachute rigger. These have been packed since the last date on the service log (on mine, the first inspection is April 3, 2000, the last repack is May 20 2002, and the last inspection is December 24, 2002). Protocol is to inspect parachutes every 30 days, and repack them every 180 days. The automatic opener--which deploys the parachute at a pre-set altitude--may be reused from other parachute harnesses and may be set for different altitudes (they have a separate inspection log--mine indicates it was installed October 18, 1991, May 15 1995, and November 2001).
A bit of history: BA-22 parachutes (along with LPU-3 life preservers, which zip onto the harness under the arms) were used onboard NASA's T-38's up until early 2003 when NASA switched to a more modern parachute rig based on the PCU-15/16 harness with a life preserver similar to the LPU-9. For example, if you look up pictures of the STS-114 crew, early photos will show them wearing BA-22's while in later photos they'll be wearing the new rig.
The service log is inside a small pouch that's behind the back pad (which snaps off with "Pull the Dot" snaps. If you've never used these before, they can only snap on and off in one direction). Also behind the back pad, you'll find a hole to access the oxygen bottle (which will also have a pressure gauge so you'll know how full it is) and a zipper that hides the rip cord pins (which keep the parachute closed).
These don't come with LPU-3 life preservers nor a CRU-60 (an oxygen connector that attaches to the bracket on the right chest strap. The emergency oxygen and the oxygen mask attach to it) though the seller might provide a CRU-60 for a few extra dollars if you ask.