Tapered Roller Bearing Cup Bore Diameter 3 1/2 in Compatible Cone Grainger Part Number 55PX78 55PX79 Compatible Cone Manufacturer Part Number 385 385A 385AX 385X 386A 387 387A 387AS 387S 388A 389 389A Cup Width 0.701 in Maximum Temperature 250 Degrees F Minimum Temperature -40 Degrees F Outside Diameter 3 7/8 in Overall Width 0.701 in Ring Material Alloy Steel System of Measurement Inch Application Forestry Mining Steel Manufacturing Housing Fillet Radius 0.03 in