Hera Integrated Rail System IRS The Hera Arms IRS is a modern designed, Quad-Rail Handguard made from high-quality aluminium and is built to handle the hardest use and abuse of tactical and competitive shooting. The IRS is CNC milled from aluminium alloy and hard coated anodized for added strength. Available in lengths of 7", 9", 12" and 15". The IRS comes with his own barrel nut where the Handguard is clamp mounted with 3 screws for additional strength. The anti-turn millings prevent turning even at the hardest use.