https://phys.org/news/2018-07-image-fenix-prototypea-tiny-pen-sized.html

In the case of D-Orbit's Fenix propulsion system, the idea was both simple and small. The pen-sized booster prototype, is just 10 cm long and 2 cm wide – allowing small satellites to work smarter and explore farther.

The 10 x 10 x 10 cm CubeSats are deployed directly into orbit from space. They currently have no propulsion system to change orbit or deorbit at the end of their missions. With the FENIX, CubeSats could be employed for longer missions farther out in space.