This article is from the Baby Proofing FAQ, by Sandra Smith, firstname.lastname@example.org with numerous contributions by others.
From: Laura Floom, Jet Propulsion Laboratory, Pasadena, CA
For a good mail order source try the Perfectly Safe Company (1-800-837-kids).
I had a gate that I bought locally, but is also available thru them. It is
wood and has vertical slats. On each side of the door frame you connect two
eyebolts. Then there are three hooks (2 on one side, one on the other) that
hook into the eyebolts. Then instead of a hook for the forth eyebolt there is
a little clamp thingy that keeps the whol thing from being taken off too
easily. You can remove the whole gate easily (and with extra eyebolts - use it
in more then one location), or you can disconnect the side with the clamp and
swing it aside, You can even collapse it in a bit. The come in two sizes. One
fits most standard doors, and the other size expands up to 96 inches. The gates
cost $19.95 for the 27"-48" model and 39.95 for the 52"-96" one. I used the
larger one to seperate the living room from the dining room. Worked great.
I am not good at describing this sort of thing.
P.S. I think it is made by Cosco, but dont hold me to it.