The AC5 is a piston-controlled first stage that represents the workhorse of the diving industry: simple, robust, reliable! At Cressi, all piston first stages feature our proprietary external direct adjustment system, reducing the regular need for replacement parts or shims, thus minimizing service costs over many years. The AC5 boasts an optimized design for maximum flow and a conical filter for improved filtration in both versions, DIN or INT. Enlarged water passage slots allow for perfectly efficient rinsing, better pressure balance, and enlarged tool housing holes for easy maintenance.