Yes, if your wheelchair cushion is less than 3″ thick, falls within the width and length measurements of the ableSeat size you have selected, and has a soft base (so the cushion is flexible).
Please note – If you plan to fly with your ableSeat and the wheelchair cushion you are inserting has a firm base (not flexible), we advise you to check with the airline what the aisle width of the aircraft is in which you are travelling, prior to travel. If the aisle width is only 17″ wide and your cushion is 18″ wide with a firm base, you will not be able to go down the aisle on the aisle chair.