BULLNOSE REGULATOR SEAL (BS110 IMPERIAL NITRILE O-RING)Bullnose Regulator Seal for use with most Bullnose Regulators, - an O'Ring which is fitted to the end of the Bullnose Nipple and supplies the seal between a Bullnose Regulator and a Bullnose Cylinder.BS110 Imperial Nitrile O-ringNitrile o-r..