For those shooters who prefer to run, or are by law forced to run 10 round magazines in their 10/22A(R), High Tower Armory developed a rotary Magazine Coupler which gives the user 20 rounds at their finger tips in one compact package. After emptying one magazine, just release, spin, and reinsert the coupler to put 10 more rounds down range. HTA 90/22 users will also appreciate the extra length of coupled factory mags when inserting them in the magwell. The mag coupler does more than just give you faster mag changes and more ammo though, it also hides a 9/64" Allen wrench which will allow you to disassemble the coupler itself, the HTA 90/22, and the factory 10 round mags Mfg: High Tower Armory