The bearings come in inch and metric sizes with retainers of 303 passivated stainless steel or zinc-plated 1144 carbon steel. The 303 types work for panels of hardness to 70 B on the Rockwell scale. For zinc retainers that number is 65 B.

Nordex Inc., 426 Federal Rd., Brookfield, CT 06804, (800) 243-0986,