Series 7200C...7220C Have A Nylon Cage, Bigger Is Machined Phenol Resin Cage Except 7226C=Machined High Tensile Brass Cage. U=ULTAGE Series. G= GM=Central Preload. P42=Dimensional Accuracy = JIS Class 4 (P4), Running Accuracy = JIS Class 2 (C2). L606