Three of the key abilities needed for making future NASA and commercial launch and in-space transportation systems more affordable and capable are: a) the ability to "live off of the land" via in-situ resource utilization (ISRU), b) the ability to reuse in-space transportation hardware, and c) the ability to leverage continuing advancements in lower-cost earth-to-orbit transportation. All of these abilities require the ability to transfer large quantities of cryogenic liquids (Oxygen, Hydrogen, and Methane) between tanks on separate vehicles. While all cryogenic rocket stages have to have a propellant fill/drain coupling for loading propellant on the ground, existing designs are not capable of in-space refuelability. A dual-purpose coupler that could be used for both ground fill/drain and for in-space refueling would be extremely valuable.In this proposed SBIR Phase II research effort, Altius Space Machines proposes continuing the development of just such a dual-purpose, lightweight, high-flow cryogenic propellant coupling to enable both ground fill/drain and in-space refueling. This coupling incorporates an innovative new cryogenic sealing architecture to enable a coupling with very low insertion/extraction forces, for manual, robotic, and astronaut-connected cryogenic propellant transfer operations. In Phase I, Altius demonstrated the innovative new cryogenic sealing architecture, and performed insertion/extraction and leak tests, demonstrating significant improvements over traditional spring-energized polymer seals, raising the TRL from 2 to 3 at the end of Phase I. In Phase II Altius will continue refinement of the cryogenic sealing architecture, and will design, fabricate, and test a family of couplers based on this architecture, and focused on an industry-provided launch vehicle application. Testing of the ground and in-space couplers during Phase II will raise the system TRL to 6, paving the way for Post-Phase II flight demonstration (yielding TRL 9).