No idea but it's a 1/4" drive so you can use whatever extensions and bits that you have already. I need to get way down in my AICS chassis so I put a 1/4" drive socket on the fat wrench and cut off an allen key that fits the chassis screws and use the socket on the fat wrench to turn it.Seems to have good reviews for the most part, Amazon has a good deal on the set $47.63 with free shipping for prime members.
Only concern at this point is one review I saw was the shaft is to thick to get the bit in some smaller spaces. Do you know if it would be able to get a bit in the recess for the 10/22 take down screw? If it is small enough to fit in that i'll order that one.