Tactical Solutions PLIV45TEMODNF: The Tactical Solutions PAC-LITE I upgrade is designed to replace your factory Ruge Mark I or Mark I 22/4 upper to reduce weight increase accuracy and improve reliability. This upgrade is easily installed and is offered in 4. and 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 - 1:1 - x 28 Threads - 11 Degree Target Crown - Stainless steel Breech face and receiver - Lightweight Aluminum Barrel and receiver - Weight: 8.5oz - Length: 4. - *Drilled and tapped for Pac-Lit Scope Bases - *Thread Protector (End Cap) Included with Barrel