Efa-Lock Setting Curlers

Now for a real blast from the past, exactly how old I'm not sure but I'm guessing between the 1930's and 50's.  A while back I acquired some Efa-Lock curlers more out of curiosity than anything else.

 The interesting thing is that they have a spring clip mechanism.

 For the longest time I was baffled as to how they might have been used. Mystery solved! The instructions are below:

 Looks like it would be really tricky to get them to stay in place securely. I'll have to try them sometime.  If anyone knows any more about these vintage curlers, when  they were made, or the styles they were used for (obviously curly), I'd be interested in hearing and tidbits of information you might have.


The back of the one page instructions has an ad for perms and (perm?) rollers. Take a look: