An assembly comprising: a first member; a second member, wherein at least a portion of the second member surrounds at least a portion of the first member; and characterised by at least one sealing ring (20, 20') comprising a shape memory alloy body extending from a radially inner sealing portion (22, 22') to a radially outer sealing portion (24, 24') in a wave-like shape comprising at least one peak (26, 26') and at least one trough (28, 28'), the at least one sealing ring (20, 20') positioned between the first and second member (110, 120), such that the radially inner sealing portion (22, 22') faces the first member and the radially outer sealing portion (24, 24') faces the second member, wherein: the radially inner and outer sealing portions (22, 24, 22', 24') are each substantially planar and extend substantially parallel to the axial direction of the at least one sealing ring (20, 20'); the at least one sealing ring (20, 20') comprises a first sealing ring and a second sealing ring; the first and second sealing rings (20, 20') are arranged such that at least one peak of the first sealing ring is aligned with at least one trough of the second sealing ring, and at least one trough of the first sealing ring is aligned with at least one peak of the second sealing ring; and the first sealing ring is in contact with the second sealing ring. a first member; a second member, wherein at least a portion of the second member surrounds at least a portion of the first member; and characterised by at least one sealing ring (20, 20') comprising a shape memory alloy body extending from a radially inner sealing portion (22, 22') to a radially outer sealing portion (24, 24') in a wave-like shape comprising at least one peak (26, 26') and at least one trough (28, 28'), the at least one sealing ring (20, 20') positioned between the first and second member (110, 120), such that the radially inner sealing portion (22, 22') faces the first member and the radially outer sealing portion (24, 24') faces the second member, wherein: the radially inner and outer sealing portions (22, 24, 22', 24') are each substantially planar and extend substantially parallel to the axial direction of the at least one sealing ring (20, 20'); the at least one sealing ring (20, 20') comprises a first sealing ring and a second sealing ring; the first and second sealing rings (20, 20') are arranged such that at least one peak of the first sealing ring is aligned with at least one trough of the second sealing ring, and at least one trough of the first sealing ring is aligned with at least one peak of the second sealing ring; and the first sealing ring is in contact with the second sealing ring. the radially inner and outer sealing portions (22, 24, 22', 24') are each substantially planar and extend substantially parallel to the axial direction of the at least one sealing ring (20, 20'); the at least one sealing ring (20, 20') comprises a first sealing ring and a second sealing ring; the first and second sealing rings (20, 20') are arranged such that at least one peak of the first sealing ring is aligned with at least one trough of the second sealing ring, and at least one trough of the first sealing ring is aligned with at least one peak of the second sealing ring; and the first sealing ring is in contact with the second sealing ring.