TruFLOW Manifold Coupling Nipple features male BSP thread on both ends and is used to make the connection between manifold parts. Primary seal for the connection is made with the attached o-ring on the nipple. Thread sealant on the nipple ensures tight bonding between the nipple and the manifold. Use Uponor Silicone Oil (A2620007), sold separately, on the male threads to ease installation.