King Arms went back into producing theses series as there is a growing demand for them... "This Knight's SR-16 E3 is a full metal constructed AEG with full markings. It is equipped with ambidextrous mag release, bolt catch and selector. The integrated bolt catch/release system makes the hop-up adjust easily accessible. Comes with folding front sight and free float URX rail system, which has 5 sling swivel slots on it. The body and stock also has a sling swivel slot on each side.