I go through about six of the taller bottles for a handheld propane torch a year. My BIL cooks mostly on a small outdoor propane grill using the short, squat green bottles. I bought a fitting through Harbor Freight which said it would refill these small bottles from a 20- or 30-gal propane tank. Dubious, but it does work. The connector goes on the propane tank and then the small bottle screws on the other end. You first freeze the small bottle, connect it to the tank, turn the tank over and open the valve. You can hear a very slight hiss if you hold your ear to the tank. Close the value to the tank and then remove the bottle. I suspect it would work at maximum efficiency if the tank were at room temperature and the small bottle right out of the freezer. Used my postal scales and it seems to refill very close to original weight. Saves me a fair bit of money over a year not having to keep buying replacement bottles.