Identify channel window balance

Thanks for writing in. See either our S351-24 or S390-24. The only difference between the Series 351 and Series 390 is the 'depth' of the bottom nylon shoe. The Series 351 bottom nylon shoe has a depth of 1", whereas the Series 390 bottom nylon shoe has a depth of 1-1/8". Below are the dimensions of each respective shoe. Compare with your old balances and see what you think matches best.

You will need to select a stamp option of 2340. 

The measurement should be perpendicular and just beneath the metal channel. Here's another way of thinking about it: stand your balance straight up as it would be if it were installed in the window. Look at the bottom shoe and think of it as just that: a shoe. Now, measure the heel to the toe. That's the depth, and it should tell you exactly what you need.