These are not easy to come accross, and they are such useful things, I can see why they don't become available all that often. 
This yellow gold hook is a decent size, and coukd be used as an extender, or as a pendant for adding charms - or both! 
The jump ring is on a swivel, so it can be orientated whichever way suits your purpose.
Tests as 9ct gold 
Weight approx 1.29g
Overall length approx 31mm 
Very good antique condition