Thanks for posting. The pivot shoe might be our 15-212, which is 3/8" thick and 15/16" wide. Please compare and let me know if this seems right.
Are you measuring the diameter of the outer tube, which is either metal or plastic, rather than the inner rod? Please be certain before proceeding. If so, and if it's indeed 3/8", then you have a S900-29. There is no black tip option for this Series 900 spiral balance. To know what color tip to select, weigh the window sash the balances support. You can then match that exact weight with one of the weight ranges listed alongside each color option on the balance shop page. Let me know if you have further questions.
