Skip to content
Block and Tackle Window Balances

Differences Between 300 and 400 Series Window Balances

One question we get frequently is "what is the difference between the 300 and 400 series balances?" The short answer is, there is no difference! These balances function exactly the same. However, there are some minor differences that may seem a bit confusing at first. Continue reading to learn about the specific differences between these two common block and tackle window balances.

Block and Tackle Window Balances


The main difference between these two balances is the manufacturer. The 300 series balances are made by Caldwell Manufacturing. The 400 series is made by Amesbury.


 Another notable difference between the 300 and 400 series balances is the stamp. The 300 series has the stamp printed on whereas the 400 series is pressed into the metal.

Additionally, the stamps look a little bit different. For example, the stamp on a 300 series balance might be "14 4" but the 400 series equivalent would be "1440."

Block and Tackle Window Balance Stamp

Here you can see the difference between the two stamps. The 400 Series the top balance and the 300 series is the bottom.


The guides for the 300 series and 400 series are not interchangeable. There are similar sized guides between the two series, but you cannot substitute guides from a different series.

These are the technical differences between the 300 and 400 series balances. These balances are interchangeable. The same stamp for a 300 series will work for a 400 series and vice versa. If you need help determining the correct block and tackle window balance for your application, don't hesitate to contact uschat with us, or give us a call at 1-800-842-0974 and one of our representatives will assist you. 

Additional Help

How to measure block and tackle balances

How to determine top and bottom guides

Block and tackle balance stamps

How to install block and tackle balances

Previous article The Significance of Winged Guides in Block & Tackle Window Balances