48lb sashes double hung

Hello. This looks like an S140-12 12 pound Coil Balance system, based on the design and the '12' stamp on the housing. Since you'd have a pair of these systems for each window sash, that would give 24 pounds of overall support for sash. Since you said in the title you have a 48 pound sash, you may want to double-check the weight. Let me know if you have further questions.