"FABRASIVE DISC UNITS TO HAVE THE FOLLOWING FEATURES: MUST BE IN THE GRIT GRADE AND DIAMETER SPECIFIED; LAMINATED,RESIN BOND,ALUMINUM OXIDE; MUST BE CAPABLE OF OPERATING SAFELY AT RPM'S; DISC MUST BE PERMANENTLY FUSED TO A METAL OR PLASTIC HUB WHICH WILL ATTACH TO A LOCKING ADAPTER BY HAND,WITHOUT THE USE OF TOOLS,THE METAL HUB FUSED TO THE DISC MUST MATE WITH STANDARD ABRASIVES INC.,LOCKING ADAPTERS; SANDING FACE TO BE CONTINUOUS NO NUT OR INDENTATION"