ZRO Delta Ready Series ZR01 Full Size .223 Wylde 30+1 16" Black Nitride Threaded Barrel, Black Aluminum Receiver, M-LOK Handguard, Adjustable Black Synthetic Stock, Black A2 Grip The Ready Series ZRO1 is the foundational offering of the Ready Series. The ZRO1 combines all of the durability and reliability the Ready Series is known for with streamlined features. Featuring an ambidextrous bolt release, 16 nitride barrel chambered in .223 Wylde, and a 15 MLOK rail, the ZRO1 is ready for your optic of choice and a lifetime of reliable service.