A very solid gun, but there aren't many accessories available. The all American classic M16-A1 sports a solid stock to accomodate a large battery. If the classic American style is what you're looking for, this is the one to own. Metal parts include magazine, trigger, bolt cover, charging handle, and bolt flap. The CAR-15 sports a compact package that's mean to look at from the receiving end, thanks to its meaty muzzle.
Stock is extendable.
Metal parts include barrel assembly, magazine, trigger, firing selector, bolt flap, T charging handle, and stock core. Comes with Hi-capacity magazine. More for the collector, the M4A1 is often preferred. Metal parts include magazine, stock core and trigger. The detacheable upper handle reveals a weaver rail mount that can take a hi-scope mount that allows you to peer over the front sight.