The UTG PRO Ops Ready S4 AR-15 Stock Kit is a complete Mil-spec stock system molded from impact resistant high strength matte black polymer. Features 4-position adjustability with a compact 4.28" length designed for optimal performance when wearing load bearing vests or plate carrier systems.UTG PRO Ops Ready S4 Mil-spec Stock KitComplete kit includes extension tube buffer buffer spring receiver end plate and castle nut4-position adjustable with 4.28" compact lengthImpact resistant high strength matte black polymer constructionFits AR-15 platformsBuilt for heavy duty use with tight tolerance controlsMatte black finishPerfect for tactical applications and competitive shooting this stock kit provides secure fit and reliable function with comfortable length of pull adjustment for various shooting positions and gear configurations.