OP05-7810 window crank handle

I know this is a casement window crank, but I can't tell which based on that number. There are two ways to measure and get the right handle. You can measure the hole inside the handle itself, and the diameter tells you what to get, or you can measure the metal pin that fits into the hole. It will have roughly the same diameter. If you come back with that measurement, I'll suggest a handle.