Not everyone has the time required to learn enough about elastomers to specify and select them properly. There are many performance requirements which defy reduction to a material specification. This paper suggests ways in which the designer can provide improved guidance to prospective vendors, or their “in house” materials group, to insure proper material selection. Included in the discussion environmental considerations (exposure to temperature, fluids, weather, sunlight) and functional considerations (electrical and wear resistance, vibration isolation). Testing methods and durability evaluation are also covered.