Caldwell KM 23 9 30# Balancer

See our S380-24 and S385-24 Channel Balances. The only difference between these two balances is the depth of the bottom nylon shoe, or the 'heel-to-toe' measurement, so compare both with your old hardware to see what matches best. See the illustration below for reference. 

Now, you'll have to choose a stamp option that determines the strength of the balance. Your old stamp 23-9 is from a rating system no longer used. We suggest weighing the window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option on the balance shop page. 

Comparison of the S380 and S385 balance shoes.