[225in1 set] -225 O-rings with separate transparent plastic storage box. [Multiple Sizes] -15 different metric sizes with outer diameters ranging from 6mm to 20mm. [Hardness] -50 hardness tester (Shore hardness), used for permeability resistance. [VMQ] - Standard silicone, temperature range from -22 ℃ ℉ (-30 ℃) to 392 ℉ (200 ℃). [Application] - Widely used in hydraulic and pneumatic seals, pressure valves, gas compressors, reaction valves, heat exchangers, boilers, filters, mechanical seals.