This article is from the Baby Proofing FAQ, by Sandra Smith, email@example.com with numerous contributions by others.
From: Michal Peri, Gordian; Santa Ana Heights, CA
We have a gate we use at the top of our stairway. It has
two spring-loaded catches on each side that clamp onto
eyelets screwed into the wall. If you unclamp the catches
on one side it swings open (the catches on the other side
act as a hinge). You can also unclamp the catches on both
sides to completely remove the gate.
It was the only gate we found that did not explicitly warn
against use at the top of stairs.
The gate is a Gerry. It cost about $20-25, I think. We got it at
HomeBase. They had a better selection of gates at a lower price than
the baby specialty stores.