The Advanced Combat Optical Gunsight (ACOG) is an adjustable telescopic sight made by Trijicon. These rifle scopes are used mainly by outdoor marksmen, hunters and military personnel. The ACOG scope was designed to be used in conjunction with the M4 carbine and the M16 rifle. Trijicon makes the scopes in a variety of magnifications with different reticles. The ACOG sight is a very common sight for Canadian forces and American forces.