Synapse (SB002B) Black Universal Synchronic Blow-Off Valve By design, it is a pull-type valve only; This means that boost pressure keeps it closed, meaning no boost leaks upwards of 100+ psi of boost Completely modular, it can be installed as a vent-to-atmosphere BOV or re-circulating diverter valve The Universal Synchronic BOV SB001 is the iconic BOV that has set the standard for impossibly fast response Patented Synchronic actuator design in Bov for unmatched fast actuation