A small high pressure bellows assembly which still has the I/D tag attached. Currently where this would have been fitted is unknown. The part would have been used to join two pieces of pipe. It is constructed so that if the gas or fluid travelling through the pipe was of a very high or low temperature it would expand or contract and would protect the pipe from buckling or breaking. The part could have been used in a variety of locations.
A similar bellows assembly can be seen here used on a Apollo J2 rocket engine