Altius Space Machines proposes the development of lightweight robotic manipulators, that utilize rollable composite STEM booms to provide a prismatic extension/retraction DOF, as robot arms for Assistive Free-Flyers (AFFs) on the International Space Station. These Low-Inertia STEM Arm (LISA) manipulators can provide comparable or better manipulation capabilities to AFFs than traditional robotic manipulators, but with less mass, lower inertial, better stowability, and the ability to reach into very hard-to-access locations. In Phase I, Altius and its partners will gather potential use cases for manipulator-equipped AFFs, derive system requirements and develop a conceptual design for the LISA manipulators, and develop a proof-of-concept prototype of the small STEM boom deployers for the LISA manipulators. This will raise the system TRL from 2 to 3. In Phase II, Altius and its partners will develop a prototype flight-set of LISA manipulators and interface hardware to connect them to the SPHERES testbeds on ISS, and will support the necessary ISS safety review meetings to get flight approval by the end of Phase II. Successful flight demonstration in a Phase II-E or II-X option would raise the system TRL to 8, at which point it could be smoothly integrated into operational AFFs such as the ones NASA STMD is currently developing.