Set of 3 Manx Norton 'square section' clutch springs - but slightly shorter than Item 0386. The reason why the square section is significant, is that the larger cross secton area of a square spring is greater than that of a similar diameter round spring - therefore in simple terms it means that comparatively, the square type springs are stronger than similar length/coil diameter round springs.
These springs were more commonly fitted to DOHC Manx Nortons (I have them fitted to my Doubleknocker), but are also suitable for SOHC M30 (Manx) Nortons and International's and should provide that extra bit of insurance against clutch slip. These springs are slightly shorter than 0386, as a customer with a later DOHC Manx told me his clutch were fitted with this length of spring, but using shouldered centre tightening bolts. These shorter springs have an un-tensioned length of 1.650" (41.9mm), instead of the normal spring length of 1.850" (46.9mm). I would suggest if you do not have an original spring as a pattern (round or square), then purchase the longer spring first