Window ballasts

No problem! We're happy to help out with this. It appears you either have the S380 or S385 balance, but you'll have to measure the depth of the bottom shoe to determine between the two. If it's 1", go for the S380-27, but if it's 1-3/32", you can go for the S385-27. 

In either case, you'll choose the 2640 stamp option to match the one on your original balance! Let me know if you need clarification on anything.