Flat-Face design Connection under pressure One-hand operated CEJN Series 664 is a Flat-Face quick-connect nipple with a built-in pressure eliminator. The nipple is according to and exceeds the demands in the ISO 16028 Standard for low- and medium-pressure hydraulic applications. The Flat-Face design minimizes spillage during connection and disconnection. The pressure eliminator allows for connection with residual/trapped pressure on the nipple side. The nipple Series 664 connects with couplings in Series 665. The pressure eliminator nipples are also available in four other sizes; DN 6.3 (Series 264), DN 10 (Series 364), DN 12.5 (Series 564), DN 19 (Series 764). For steel couplings in accordance with ISO 16028 see Series 665.