The Invacare HomeFill II is a multi-stage compressor that allows patients to refill custom, high-pressure portable oxygen cylinders at home. It eliminates reliance on delivery services and gives ambulatory users the freedom to leave the house for extended periods. The device connects to a compatible stationary Invacare oxygen concentrator (such as the Platinum 5, 10, or Perfecto 2). It extracts oxygen from the room air, purifies it, and compresses it into small, lightweight portable cylinders. Users can fill their own tanks while simultaneously receiving continuous oxygen from the concentrator.