I have an Airsep Airbelt battery and also an external power cartridge with desktop charger, both compatible with Airsep Focus and Airsep Freestyle POCs. Both are in good status and have been used until recently. I bought the Airbelt and its charger second hand in this forum for £200, and the external power cartridge for £315 brand new from Intermedical, both around 6 months ago. Combined with the Airsep Freestyle at 2lpm, they allowed my dad to take long haul flights and be off the grid for up to 7 hours a day.
Unfortunately, he will not be needing them any longer. I don't want any money for them, but will be happy to give them to anyone willing to pay for the shipping costs and to place a reasonable donation for the British Lung Foundation.