Series 7200C...7220C Have A Nylon Cage, Bigger Is Machined Phenol Resin Cage Except 7226C=Machined High Tensile Brass Cage. C=15˚ Contact Angle. DBT=(Segment Pairing, Code QBT)=Quadruplex Set Of Bearings In A Combined Tandem/Back-To-Back Configuratio