Rubber Coupling Insert, For Coupling Size FC20, Maximum Torque 250 Inches per Pound, Color Black Boston Jaw CouplingsOil-Resistant Synthetic Rubber SpidersRecommended where minimal noise is desired, particularly at motor speeds.Standard tolerance: +0.001/-0.000", all bore dimensions. 3-jaw insert design is complete with keyway and set screw. No lubrication required. A complete assembly requires 2 hubs and 1 jaw-coupling spider, sold separately.Temp. range: -32 to 200 F (-35 to 93 C)