Fit the scenario and balance cost-effectiveness. Below are the core classifications and selection guidelines.

I.Classification and Characteristics of Washer

　1.Ordinary rubber washer: Low cost, simple structure, suitable for light-load indoor fixing and meeting basic sealing needs.

　2.EPDM rubber washer: Excellent weather resistance, acid and alkali resistance, and water resistance, suitable for outdoor, humid and other complex environments.

　3.Bounded washer: With metal base + ordinary rubber/EPDM rubber layer, they have strong pressure-bearing capacity and good sealing performance, suitable for outdoor heavy-load and high-protection scenarios.

II. Precise Selection Suggestions

　1.Light-load indoor use (no special protection) → Ordinary rubber washer;

　2.Outdoor, humid/salt spray environments → EPDM rubber washer;

　3.Heavy-load and high-protection requirements → Bounded washer (metal/Aluminum/Stainless steel base + EPDM rubber layer).

Core of selection: Choose on demand to avoid waste, and balance practicality and cost.