Spiral balance blue tip on 12" tube?

Welcome to SWISCO. If your tube measures 12 inches long by 5/8 inches in diameter, and you have a tilt window, you can use our S600-12. Measure the diameter of the metal tube (the one by the tape measure in your photo) to verify. You should weigh your window sash to confirm that you need a blue tip, for a window sash weight of 10 to 26 pounds. If your diameter is 3/8 inches, please let us know.

I'm sorry, I'm confused. In your first post, you said the tube is 12" long. Looking at your photo with the tube next to the ruler, that appears to be accurate. You don't want to measure the inside spiral or spring, just the outer tube.

If the tube in your second picture is broken so that it's smaller than its original length, you will need to measure a balance from the same window that isn't damaged to confirm what size you actually need.