this is a double function rod. where it can be used as an extension bar that can be used with a ratchet handle or a sliding T handle and on the other hand when it is used in sockets, it can be turned by hand like a screwdriver. That's great. and I rarely find drivers with a size of 3/8 sq. but have a square hole on the back. if for the size of 1/4 sq. it is very much and there are several variations and prices worth the manufacturer that make it. It has a nice design too and a comfortable grip so it can be rotated by hand without slippery ... you should have this attachment to work with the 3/8 ratchet handle you already have.