The ones I am familiar with are little bigger than a pc, with a handle and castors so can be wheeled to a patient in a bed or wheelchair. They have a small diaphragm pump ( You can buy something similar for inflating tyres, balloons, air beds etc quite cheaply) Using these machines means no oxygen cylinders or gas reticulation required for patients who have depleted lung efficiency. As those little pumps are so freely available, Israel"s excuse for siezing the machines is suitably pathetic.
Shots fired from northern Gaza at IDF forces stationed at border, no casualties (Haaretz)
from the article: Report: Israel seizes oxygen machines donated to PA