Exhaust nut (rose), Norton twins, 1949-1973, naval brass plated as per original, 3/4" thread. Cylinder head exhaust port to exhaust pipe threaded nut, pair. Norton 500, 600, 650& 750 twins. NOTE: Prior to fitting you must remove any dirt, carbon or sealant. Deeper finning, RGM style - use Special spanner R-050654 with 3 points of contact to avoid bent fins and improved removal. Original Part Number:D12/167, 18092, 062464 - Exhaust pipe locking nut (cylinder head)