S63 Standard Barrel Back-Black Necessity the MXR is built to

the MXR is built to perform flawlessly in any condition

removable barrel with A5 threads

quiet shot while maintaining optimal efficiency

Standard O-Ring for Valve Face Seal:  The use of a standard 011 90D O-ring for the valve face seal makes it easy to perform rebuilds and maintenance

S63 Standard Barrel Back-Black Necessity the MXR is built toThe S63 is the most advanced Planet Eclipse barrel system yet! Introducing the Eclipse PWR Inserts and 3 piece construction, the S63 offers exceptional shot consistency, precision and control. This S63 barrel back is part of the S63 3 piece barrel system that is standard with the Gtek 180R and is compatible with all other parts of the S63 barrel system. S63 Barrel Back Compatibility: + S63 Pro Tip + S63 Tactical Adaptor + S63 Tactical Extended Adaptor