23"

Hello, thank you for posting,

To further review, are you able to show us additional angles of the top and bottom nylon attachments? I am trying to confirm if they have a "winged" out style or not. Thank you! 

Thank you!

It appears you have either the Series 351, with a 15-002 bottom attachment, or Series 390, with a 15-001 bottom attachment. Take a look at the image below to determine which balance you'll need. You will need a 23" balance with a 2240 stamp option.

Please review and let us know if you have any additional questions.

Comparison of the S351 and S390 balance shoes.