The weak facet hand placement is effective without having a special thumb rest. Thumb relaxation from Ronni is effective on MCK If you'd like. Shoulder strap attaches on either. No pistol brace extension desired. MCK uses pistol's slide launch so no mal-features like Ronni. The one thing the Ronni has https://marioqdpyh.buyoutblog.com/26102714/about-glock-recover-kit