Durometer is the hardness of a material. You will need to specify the durometer of all the shoes rubber, foam and plastic parts. You will need a 2 different durometer testers. Asker “C” is the EVA standard. 25 “C” is very soft, 55 “C” is a standard midsole 85 “C” like wood. For rubber plastic you will need a Shore “A” tester. For a rubber outsole Shore “A” 55 is good for rubber. Above 60 your rubber will be stiff, heavy and slippery. The durometer scale was defined by Albert Ferdinand Shore, who developed a measurement device to measure Shore hardness in the 1920s.

Shore 20A = Rubber Band, Shore 40A = Pencil Eraser, Shore 60A = Car Tire Tread, Shore 80A = Leather Belt, Shore 100A = Shopping Cart Wheel