This is a high-pressure compact quick disconnect system offering bi-directional full flow with no shutoffs used by Dive Gear Express in our DGX Gears blending and transfill system of components. Use these brass 1/4-inch NPT fittings to interface other equipment with the QF4 style quick disconnect fittings in our Deluxe Hose Kits for booster and transfill. The pressure rating when coupled is {4000 PSIG @ 70 °F | 275 BAR @ 21 °C}. The connection must NOT be uncoupled while under pressure. These raw brass fittings are NOT suitable for use underwater.