Went into a little junk shop in town earlier and left with this pair for £8, that's a little under $13. Both in the wrong tatty boxes but I think I'm right in saying that the on on the left is a Slim Adjustable (L4 1966) and the one on the right is a Superspeed (Brit pat 694093) with II stamped under the head. Bought to use and they need a good clean but the adjustable clicks round nicely and the doors both open smoothly. Damn I thought I had my RAD under control
I found a "Slim" last summer in about the same condition. But no corrosion. Cleaned up beautifully and is now retired in my lil collection. Fogey
According to this thread http://www.theshaveden.com/forum/showthread.php?t=9206 its an English Super Speed (#18) and is "uncommon" ; Which is nice (Although being in England I suspect they are easier to stumble upon.)
So i see. The gap at the bottom where you twist is considerably smaller than the rocket. So i like i say, a nice find