Never tried this, but was told that you could use it as a variable fuse (when doing current measurements). Just pop the button back in should it exceed the max
For Pete's sake don't use the moving coil AVO, ie the 8, as described. The method of calibrating that MECHANICAL circuit breaker gives about 2.5 times f.s.d. on the movement.
I've always made myself stand in the norty corner when I pop that.
The Rapid page does show the older type, but I wondered if they may stock more up to date stuff now.
BTW...They started in a Nissan hut near Boxted airfield 20 or so years ago. It's a sight to behold now.