Pressure relief valves are great for expelling pressure build up in your lower casting that comes from temperature and elevation changes, but they have one problem: you must remember you activate them. With our new ACV (Automatic Casting Vent) technology, that’s no longer the case. These vents are set from the factory to blow-off when pressure levels rise enough to influence your effective spring rate, keeping your ride consistent regardless of environmental factors. Two ACV vents are found on our highest-end air-sprung forks with the EssenTTial damper, while only one is needed on forks with the Lift Damper. With the Lift Damper taking up less leg volume than the EssenTTial Damper, pressure never builds in the damper leg of Lift-equipped forks to necessitate venting.