APEM, Grayhill, Omron,
I'm not sure where RS gets theirs, but it may be from one of those suppliers anyway.
I just don't trust radio shack switches anymore after the bad contact zapped the programming on my CF.
It may work fine for you, as RS switches are really hit or miss. If it's working for you then you're probably okay with that one.
It's just the lockup button right?