The black PUR hollow round rod is 40 Shore A and meets American Society for Testing and Materials ASTM D624 specifications. PUR (polyurethane) provides better tear and abrasion resistance and can be more readily bonded to another material than UHMW polyethylene. A hardness measurement of 40 Shore A means the material is medium-soft for a balance of good formability and good resistance to surface penetration.
Rubber is a strong, flexible material that provides good insulation and shock absorption. Some types of rubber may be weather or chemical resistant and withstand high temperatures. Wear resistance is the degree to which the rubber resists abrasion. Hardness is measured with scales Shore D, Shore OO, and Shore A, which is the most common scale. A higher number means the material is harder and more resistant to penetration. A lower number means the material is softer and more flexible. Tensile strength, used to indicate the material’s overall strength, is the peak stress it can withstand before it breaks.