JMac Customs ZERO 5/8-24 Facemount HUB Black. 375-24 thread pitch while maintaining the shortest overall length possible. By itself the ZERO does not offer flash or recoil mitigation. It does however offer the user the ability to configure their firearm by attaching the device of their choice. The ZERO-30F-X37 is compatible with the TP-37 BDS-37 and BDS-37-EXT. Specifications for JMac Customs ZERO 5/8-24 Facemount HUB: Manufacturer: JMac Customs Fabric/Material: 17-4 Stainless Steel Color: Black Threads per Inch: 5/8x24 Weight: 3.5 oz Package Contents: JMac Customs ZERO 5/8-24 Facemount HUB JMac Customs Zero-30F-X37: ZERO 5/8-24 Facemount HUB Black