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 length. Available in Gun Metal Gray. 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