Identify Channel balances to purchase replacement

Hello, thank you for posting,

It appears you have either our Series 351, with a 15-002 bottom attachment, or Series 390, with a 15-001 bottom attachment. Take a look at the image below and measure to determine which balance you'll need. 

Check the metal channel for a number that will indicate the spring strength stamp option you need. If there are no markings, you will need to obtain the weight of the window sash and compare to the strength chart on the product page.

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

Comparison of the S351 and S390 balance shoes.