1.Material : 50# 65Mn 2.Color: black, bright,blue, yellow 3.thickness ... rolled, high carbon ,hardened and tempered spring steel strip 1. Material : 50# 65Mn2.Color: black, bright, blue, yellow 3.Specification : thickness ... clutch patch , reeling shutter spring steel strip, horologe clockwork spring ,shoes material ,hook material, spin ,standard stamping ,packing strip, and other industrial-used ...