Check the listing for details. Zeagle Envoy/RaZor II Regulators. Condition: New. Listed at 389.95 USD. The Flow-by Piston design of the RaZor 1st stage provides much greater reliability and serviceabilty compared to conventional designs, while improving responsiveness and performance at all breathing ratesThe Envoy RaZor regulator has a Flow-by Piston style 1st stage with design features that allow direct airflow through the 1st stage, providing performance that far exceeds what would be expected in an economical regulator. The 2nd stage is a balanced orifice designThis 1st Stage sits direct atop a Tank Valve section the threads into any standard 3/4-14 NPSM Scuba Cylinder. This combination saves space and increases efficiency making it ideal where weight and space are critical such as stage bottles and fully redundant systems. Yoke Transfiller fills through the RaZor 1st stage from a SCUBA cylinder (Included)