Get Benchmade Omega Spring UK. These are aftermarket omega replacement springs for large and small benchmade series of knives. Small will fit benchmade 940 series of knives along with the 555, 556, 557 mini griptillian.
It's shiny so i am guessing it's stainless.
Perfectly described and promptly delivered! The spring measures a consistent.021 inch od thickness throughout. Benchmade 940 spring broke again. May fit other larger sized bm knives but i have not tested and am not.