Denise,
The hole locations are not supplied by the manufacturer. These blades are made by Craftmade for specific Craftmade fans and there is no way to know if the hole patterns will match up with other brands...and likely they will not. If you are looking to change the blades on your existing fan, it is best to search for blades by that manufacturer and for that specific model. Do you know what brand and model of fan you have?
Greg