The necklace is 18 inches around and extends to 20 inches. If you need it to extend further let me know and I can add more of an extender chain to it. I can also shorten the cord. If you want to know what size would be best for you, take a piece of thread and put it around your neck at the length you would want your necklace. Then measure the thread.
The bail connecting the guitar pick to the cord may be different on the one you receive than the one in the picture. I am currently in the middle of changing the bails to ones less likely to tarnish. It will be the similar style, but not exactly the one in the picture.
I used a lobster claw clasp as a closure, but if you prefer a barrel or toggle clasp let me know and I will change it. I can also change the cord if you prefer a different color, or suede. Suede is available in limited colors.