The Canadian Atmospheric Laser Absorption Spectrometer Experiment Test-bed (CALASET) is an interdisciplinary project that aims to develop and test instruments capable of measuring trace gas concentrations on stratospheric balloon flights. In recent years, sensors utilizing non-dispersive infrared (NDIR) technology have greatly improved in their precision and reliability, resulting in broad deployment of these sensor for atmospheric research. To assess the potential of this technology for balloon-borne measurements, the CALASET team has developed an NDIR-based instrument to measure trace gas concentrations on a long duration stratospheric balloon flight (TRANSAT). The instrument is based around a Licor (LI-850) trace gas sensor which measures CO2 and H2O with quoted precisions of 1.5 %. The flight is projected to launch in June 2024 from Kiruna, Sweden, north of the Arctic circle. Lasting approximately 5 days, it will traverse the north Atlantic Ocean and land on Baffin Island, Canada.  I will discuss the development of the instrument from its origin as a undergraduate student project flown in 2022, to its current state in preparation for the TRANSAT flight. Additionally, a proof-of-concept version of the instrument was launched from Timmins, Ontario in August 2023 in preparation for the TRANSAT flight. Using the results from this flight I will address the performance of the instrument focusing on the modifications that were made for the TRANSAT flight.