Milgard window 15" metal Channel Balance

Thanks for writing in. This looks like an S385-15 to me. The only other possibility is the S380-15. There is just one difference between these two balances: the 'depth' of the bottom nylon shoe. The Series 380 has a shoe depth of 1", while the Series 385 has a shoe that is 1-3/32" deep. Now, in your third picture you show a measuring tape parallel to the heel and toe of your old balance's shoe; this is how you would measure the depth. It certainly looks a bit bigger than 1" in that photo, which would suggest you have the S385-15. But pictures of measuring tape can be very deceiving, so I encourage you to double-check this measurement to be safe. Anything greater than 1" will suggest you have the S385-15. 

Finally, you'll need to select a correct stamp option as well. Use a stamp option of 1440.