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