What are they, and how do they work?

Thanks

James

An arrow insert fits in the front and rear of the shaft. The front insert is threaded for screw-in points and the rear insert is normally an aluminum flat nock or a half moon nock.

They make a piece of tubing...intothe beginnings of anarrow.

Mike

In case you're thinking about a (brass) insert, it's a heavier than normal insert that is glued into the front of the arrow to make it more front heavy (Google FOC for explanation). Aluminum inserts weigh about 40 grains whereas brass ones weigh around 100.