6-24 months is an age range which most baby gates are certified for by independent testing organizations.
The common belief by testing organizations is that beyond 2 years children start to become strong enough and smart enough to open most baby gates.
A small child wouldn’t figure out the lock on the Retract-A-Gate baby gate unless they were shown how, since you have to push down and turn at the same time (kind of like child-proof caps).
Retract-A-Gate is designed to be very easy for adults to operate, but would be difficult for small children to open the baby gate.