From Colt: Designed for the plinker, serious shooter or varmint hunter, Colt s CR6720/CR6724 is a direct descendant of the rifles that made Colt “the small-arms sensation of modern warfare , the original AR-15 design from 1963. The CR6720/CR6724 has many features that make it right at home on the range on in the field. A flat top receiver will allow for many types of optics and a tubular handguard is comfortable for all day long shooting. With its full floated 20 or 24” stainless steel heavy barrel and enhanced trigger and hammer, the CR6720/CR6724 lives up to its name as the Colt Accurized Rifle. The CR6720/CR6724 is the perfect choice for the shooter who wants the look and feel of the original, but requires the accuracy of a modern semi-auto rifle.