... the customer’s request, and not need to machine a new mold. Type 21. Pure rubber, with no reinforcement2 ... the customer’s request, and not need to machine a new mold. Type 31. Pure rubber, with no reinforcement2 ... customer’s request, and not need to machine a new mold. Type 41. Seal consists of inner and ... the customer’s request, and not need to machine a new mold. Type 51. Pure rubber, with no reinforced ...