THIS IS A REPLACEMENT TRIPLE GROOVE CRANKSHAFT PULLEY FOR LONG WATER PUMP SMALL BLOCK CHEVYS. IT HAS THE STANDARD BOLT PATTERN TO MOUNT ON ANY CHEVY BALANCER. THIS IS THE REPLACEMENT TO THE 3 GROOVE PULLEYS THAT WERE USED AFTER 1968 ON CARS AND TRUCKS WITH A/C. IT MEASURES 7.8 INCHES IN DIAMETER