This ASA use's what CP calls "System Bleed" and "Virtual Resistance" Due to the fact that it has virtually no resistance at all while turning it on or off. System Bleed will bleed all the air from your tank lines allowing you to easily remove your tank after degas. The unique design of this on/off asa allows the screws to pass through the middle of this part, so that you can mount this directly onto the bottom of your paintball marker. When purchased from PB Sports, it comes as shown with screws and 1/8 NPT plug.