Properly align your eye level to get the most accurate view out of your optics. These cheekpieces install instantly on most collapsible stocks. The rugged glass reinforced polymer withstands harsh conditions. Includes one 3.8"L x 2.12"H CPI cheekpiece (fits AR-15/M-16 stocks) and one 5"L x 2.5"H CPII cheekpiece (fits M-16 stocks). Imported.