I acquired my Air Space Devices Saf-T-climb from John Murray, 1993.
The Air Space Devices Saf-T-climb is 245 mm. tall, 100 mm. wide, and 62 mm. thick. Mine weighs 1870 g.
This heavy device is a safety that works on a notched pipe that would be permanently fixed beside a ladder. I noticed such a pipe near the ladders on the outside of the U.S.S. Abraham Lincoln's island structure, and presume that this sort of device would be used there.
There are two attachment points. It appears that the upper one must be attached to the climber's harness for the device to work. By leaning back, the climber applies tension to the upper chain, which pulls the catch out of the notches in the pipe. I haven't tested the device, so I'm reluctant to guess how well it works. One thing is certain though: it is heavy (nearly 2 kg).
By measuring the device, I assume that the outside diameter of the pipe would be about 35 mm. (1-3/8 in). Needless to say, this isn't a normal caving or climbing device, at least not with our current techniques!