Four types of elastomer designs and materials are offered to allow for flexibility in addressing specific application requirements. Standard Materials: NBR (Nitrile Butadiene Rubber) -- Buna N (Black) Considered the standard and most economical for jaw coupling spiders Offers the best combination of temperature and chemical resistance, misalignment, and dampening ability Only material suitable for reciprocating engine applications 80A Shore Hardness Temperature Range - 40° F to 212° F (-40° C to 100° C) Resembles natural rubber in resilience and elasticity Urethane (Blue) Greater torque capability than NBR (1.5 times), provides less dampening effect and operates in a smaller temperature range Good resistance to oil and chemicals Not recommended for cyclic or start/stop applications L050 to L110 Shore Hardness 55D, L150 to L225 Shore Hardness 90-95A Temperature Range -30° F to 160° F (-34° C to 71° C) Hytrel (Tan) Flexible elastomer designed for high torque and high temperature operations Excellent resistance to oil and chemicals Not recommended for cyclic or start/stop applications 55D Shore Hardness Temperature Range -60° F to 250° F (-51° C to 121° C)