I got two of these old Olt calls, they are both F-6 models. They are about 1"x1"x3.5" long, small hard rubberboxes with a thin wood plate screwed to the top. One box is rectangular and looks newer than the other which has rounded ends like the one below.

How do they work? I tried a plastic striker on the wood lid but nothing. I got this photo off the web but it doesn't say what the striker is made of.

HJ?

A small piece of wood is usually used on these type calls as a striker. Some used slate strikers and the directions would often say can be used on gunstock, too. Tom Gaskin sold a ton of his "stopper calls"--same type call, different version. Here's a similar one depicted in Davis' classic, The American Wild Turkey. Top drawing, right corner, call in use. Bottom left hand corner, chalking lip. I like to hold the call between thumb and second finger in left hand and strike with striker in right hand, held between thumb and second finger. Some strike with call and hold striker still.:

Speak of the devil. Here's Tom Jr. using one of his dad's calls:
http://www.youtube.com/watch?v=RaE7_yR1IOA