THIS IS A NEW BDS ALUMINUM ACCESSORY SINGLE VEE PULLEY,THE SIX HOLE PATTERN IS THE SAME AS CRANK HUB OR BLOWER PULLEY,IT MEASURES 6-1/4"ACROSS,WITH A 1/2"CENTER HOLE,THERE IS A STEP ON EACH SIDE THAT MEASURES 2"FOR BLOWER PULLEYS & HUBS TO PILOT ONTHIS PULEY STACKS TOGETHER SO YOU CAN MAKE DOUBLES OR TRIPPLES.PLEASE SEE MY OTHER AUCTIONS.