Piston Groove Top Nut Piston nuts are made of various materials, depending on their strain and purpose. We can manufacture piston nuts for various piston rod sizes and designs. You May LikeReciprocating Compressor Piston RingsConcentric ValveRubber O RingsMarine Compressor Spare PartsConnecting Rod BearingsPtfe Backup RingsReciprocating Compressor Crankshaft