Our Steel Low Profile Gas Blocks will fit almost any handguard design. Minimal-profile replacement for factory front sight/gas block won’t interfere with extended-length tactical forearms, while ensuring proper function of the gas system for reliable cycling. Protrudes only .4" above barrel, covers less than 1" of barrel length, and adds only 1.5 oz. of weight. Compatible with M4-style carbines and M16A2/A3/A4-style rifles with any length, .750" O.D. barrel. Two steel set screws keep the block securely anchored to the barrel to prevent shifting even under the force of full-auto recoil. QPQ Finish provides the best corrosion protection and gives a smooth black color that matches Nitride, Melonite and QPQ barrels.