1.HB: bottom flame retardant rating
2.S136 and S136H are the marks of H for preheating steel, generally through hardening and tempering to about HB 290~330
And one is S136
SUP is twice as expensive as S136
The S-136H is pre hardened without quenching
3. requirements for the high degree of mold finishing such as the production of hard rubber (PS) and super glue (ABS) and quenching model M202 high quality pre hardened plastic mould steel, M238 super pre hardened plastic die steel, high quality M300 pre hardened mold steel, M310 corrosion resistant mirror mirror die steel, corrosion quality W302 heat-resistant die-casting die steel, K460 steel, K110 deformation and abrasion resistance of high chromium steel ductile deformation.