Not sure of the series

Hello,

From what I can see, It looks like neither the top or bottom attachments has wings, so you could have either our S351-25, with a 15-002 bottom attachment, or S390-25, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. You'll also need a 2430 spring strength option for your replacement balances. Thank you!

Comparison of the S351 and S390 balance shoes.