Same drawing, different rubber compound — service life can differ several times over. Choose by three factors: the medium it touches, the temperature, and how much wear it takes.
NBR (nitrile): the best oil resistance. First choice for parts exposed to engine oil, hydraulic oil or fertilizer, such as gaskets and oil-seal type parts. Weather resistance is moderate — avoid long exposure to direct sunlight.
EPDM (ethylene propylene diene): outstanding resistance to water, weathering and aging. Ideal for parts permanently exposed outdoors and for rubber valve seats in water treatment equipment. Weakness: not oil-resistant — never use it where it touches oil.
Polyurethane: the highest abrasion resistance, suited to high-wear stations such as carrier rollers for conveying chains and guide wheels for elevating chains.
For hardness, Shore A 70±5 is common for agricultural rubber parts; check the working temperature against −30°C to +100°C. Every product page states material and hardness on its spec sheet. If unsure, send us your working conditions and we will help you choose.