I read the article in the files and the above post is correct. They are not all the same. I made one where the transmission slid right into the shaft of the arrow. On this pen I had to make a shim.
If you give it a try and don't have any arrows try your local pawn shop. I stocked up yesterday for a buck an arrow (approx. two pens or three per arrow.) Lots of variety at pawn shops. Next time I go I'm gonna try a trade.
I posted one of my pics on facebook and already have an order.
THE IAP LIBRARY ROCKS!!!!!!
-Denny- NC