It appears that the part that Rhinelandarms is selling there is a "chassis" which attaches to your 10/22 reciever, trigger housing and barrel. An AR-15 stock can then be attached to the back of the Rhinelandarms part. The advantage of this would be the ability to use any of the many available AR-15 stocks. Mounting an AR-15 stock to your 10/22 without a part like the Rhineland arms piece would take considerable fabrication. Not sure who sells these north of the 49th. I am sure whoever sells the Rhinland guns might be able to source the stock for you.