The Mk4 features EML 4 handguards feature M-LOK slots at 3, 6, & 9 o'clock positions and a full length picatinny top rail for accessories as well as an integrated handstop; Radial Delayed Blowback operating system; full kit of ZEROED parts including: pistol grip, drop-in trigger, 60/90 degree ambi safety, linear compensator 9mm, ambi mag catch, extended mag release button, AR15- ambi charging handle, bolt catch and polymer dust cover. Includes Glock 30rd magazine.