Antique Pocket Door Key :
This is a fairly common style of an antique pocket door key. The top is a propeller shape and the length of the key is adjusted by a screw at the end of the shaft. The construction of the screw mechanism is quite interesting. The key is in 3 pieces: 1 a long shaft connected to the propeller shaped bow with a female screw location inside; 2 a hollow piece with the visible portion of the shaft, the bit, and a larger female screw location on the very tip; and 3 a screw that has a wider section on the end to screw into piece 2 and a narrower section to connect into piece 1. When unscrewed entirely the length of the key can be adjusted and the shaft can even be turned. I apologize for not having pictures up of this feature; but upon request I can take pictures and post them.
Picture illustrating location of screw mechanism:
Picture showing propeller end of key:
Another view of the entire key:
