Specifications : Standard : ISO 13337, ISO 8752, ISO 8750, ISO 8748, ISO 8751 Material : Hardened spring steel Surface Treatment : Thermally blackened, zinc passivation Standard : ISO 13337, DIN 7346 Sizes : As per the attached PDF file Material : Spring steel, EN 42J, CK 70-80, SAE 1070-1080 Hardness : Heat treated to 420-520 HV Surface Treatment : Thermally blackened, zinc passivation, Phosphated