The Tactical Solutions PAC-LITE IV™ upgrade is designed to replace your factory Ruger® Mark IV™ or Mark IV™ 22/45™ upper to reduce weight increase accuracy and improve reliability. This upgrade is easily installed and is offered in 4.5” and 6” barrel lengths. Available in Gun Metal Gray Matte Black and Matte Olive Drab. The improved balance and accuracy of the Pac-Lite makes shooters feel like a pro. Installation on your existing MK frame is a cinch without the need of a gunsmith. - Rate of Twist - 1:16” - ½” x 28 Threads - 11 Degree Target Crown - Stainless steel Breech face and receiver - Lightweight Aluminum Barrel and receiver - Weight: 8.5oz - Length: 4.5” - *Drilled and tapped for Pac-Lite™ Scope Bases - *Thread Protector (End Cap) Included with Barrel