Which one should i use?

That looks to be a pretty typical tilt window spiral balance. As long as the tube is 3/8" in diameter then our S900-35 should work perfectly fine.

They don't make these without colored tips. That particular feature is necessary to determine what the calibration of the spring is going to be. Since your balance lacks a tip to use as a reference, your only option is to weigh the sash on a scale and refer to the chart we show on the S900-35 store page.

To be clear, a lack of a tip does not itself signify spring calibration. It's more likely that yours just broke off or deteriorated over the years. Weighing your sash will be necessary.