The Tactical Solutions PAC-LITE I upgrade from Tactical Solutions PLIV45TEGMGRF is specifically devised as a replacement upgrade for your original Ruger Mark IV or Mark IV 22/45 upper. The purpose of this upgrade is to heighten accuracy, lighten weight, and enhance reliability. The PAC-LITE I upgrade comes with an installation process that is a breeze, fitting perfectly onto your existing MK frame without a requirement for a professional gunsmith. Its length is set at 4.5 and it\'s available in a durable Gun Metal Gray finish.The noticeable improvements in balance and accuracy with the PAC-LITE upgrade will provide shooters with a professional shooting experience. Also, its features include a Rate of Twist at 1:16, x 28 Threads, and an 11 Degree Target Crown. The receiver and breech face are composed of durable stainless steel and the barrel and receiver are made of lightweight Aluminum. The weight of the PAC-LITE upgrade is only 8.5oz and its length is 4.5.Other notable feature is that it comes pre-drilled and tapped for Pac-Lite Scope Bases. A Thread Protector (End Cap) is also included with the barrel shipment.