Pale Blue PBR-50 is a water vapor propulsion system in a Φ250 x 300 mm form factor. It is a fully integrated system that incorporates thruster head, fluidics, electronics and propellant tank, and is clusterable to meet a wide range of spacecraft sizes.

The PBR-50 uses water as propellant and does not require a high-pressure storage. The propellant is preloaded to the tank prior to delivery from factory so that satellite integrators would not have to deal with complex fueling work.