Safety is the first concern in any nitrous system! Any IHRA or NHRA sanctioned track will require these bottle valve racer blow-off caps in all classes when you run nitrous oxide. These are safety devices that fit on most manufacture’s bottle valves. If your nitrous system creates too much pressure, one of these caps will allow it to bleed off through the vent tube(sold separately), which exits outside the vehicle. These adapt to a -8 A-N style fitting. Bottle MUST be empty to install or replace disc. Proper torque on a racer safety is 15-17 ft/lbs. Over tightening WILL RESULT IN PREMATURE FAILURE! These are the same racer safetys that come in all of our complete bottles.