ASCO series E290 valves feature a 2/2 NO – entry under the disc, which simply means the fluid going through the valve goes underneath the disc. These valves are in conformity with Regulation (EC) 1935-2004, the material of the wetted parts are listed in the chart of the Annex I of Regulation (EC) 1935/2004). All plastic parts are FDA approved, high flow due to angled seat design. Anti-waterhammer design (fluid entry under the disc). High performance, maintenance-free stuffing box.