What? ....You saying I can not use a 1/2 inch wrench to remove a 9/16 bolt?
Just Kidding!!!
With the chain and sprockets, it is best to match 520 to 520 and 525 to 525...
The 520 sprockets are 1/4 inch thick.
The 525 sprockets are 5/16 inch thick.
You could use the 520 sprockets, on the wider 525 chain...
But, you can NOT fit the wider 525 sprockets, on the narrower 520 chain...
Luis