This S71911ACB/HCP4ADGA bearing is a Super Precision angular contact bearing with 2 rubber seals, a 25° contact angle and the balls are hybrid ceramic, also known as bearing grade Silicon Nitride. This is a universal fit double set of bearings with a light preload and a P4 precision rating. The bearing's dimensions are 55x80x13. The B design bearings are designed for high-speed operation and are best suited for lighter loads. Often used in Machine Tools, or other precision applications, these bearings are known for their high-speed capabilities, robust seals, and superior accuracy.