29 " 900 series with a black tip.

Hello,

We'd be happy to help but since the black tip doesn't correspond to one of our strength options, we would need to know the exact weight of your window sash to confirm the corresponding color for your replacements. I'd also recommend confirming that the diameter of your balance housing tube measures exactly 3/8". If it's larger, you may need a different type of spiral balance. Thank you.