This adapter will allow you to refill the green 16.4 oz propane BOTTLES (Coleman, Worthington, etc) or the blue 14.1 oz BernzOmatic from a standard 20 lb (5 gal, well 4 gal if fitted with the 80% fill valve limiter) TANK. (I refer to the cylinders as bottles and tank for clarity below.)Some tips for a satisfactory refill:You DO NOT need to freeze or warm anything. The bottles DO NOT have to be empty.You DO need to wrap a couple turns of teflon tape around threads of the adapter and then tighten it onto the tank BY HAND until it seats - if it becomes hard to turn after a twist or two you are cross threading so back it out and start again. If you force it on with a wrench when cross-threaded it will leak and cause you needless frustration, so tighten by hand. Now take a wrench and give it another 1/2 turn or so. You want adapter tight on tank so that it doesn't come loose when screwing on and off your bottles.You DO want to transfer only the liquid propane from tank to bottles. This means you will have to lay tank on its side if more than 1/2 full and completely upside down if less than 1/2 full, otherwise you will just fill bottle with gas.You DO want to LOOSELY HAND TIGHTEN your bottle onto adapter. It DOES NOT need to be cranked on. It won't leak. Just snug it up using your thumb and a couple of fingers. Now open valve on tank. You will hear the liquid swishing into the bottle. Wait until you can't hear it anymore. If your bottle was completely empty this will take about 10 seconds and your bottle will be about 1/4 full (maybe 1/3 full if you heat tank and freeze bottle) but it doesn't matter. Now see that 1/4 inch hole with the pin in the middle on top of your bottle? That is a pressure relief valve. You can take a pair of needle nose pliers (the kind with the tangs bent at 90 degrees make this easy) grasp the pin and pull it up a tiny bit. Gas will vent out from bottle and the swishing sound of more liquid going into the bottle will resume. You can continue to let out gas until liquid spews out (careful, it's very cold). If you have the bottle turned so that the valve is at the top half of your horizontal bottle when the liquid spews out, your bottle will be about 90% full. Release pliers, close valve on tank, and unscrew the bottle. You will hear a little whoosh as it comes off adapter. Take a fingertip full of petroleum jelly or vegetable grease and wipe it into the relief valve hole. It should stay there. If not, you can wiggle pin to get valve to seal. If it takes a lot of manipulation to get it to seal, don't refill this bottle again, because you probably bent the pin. If it will not stop leaking, not to worry. You can either place bottle on a stump and from about 100 yds shoot it with your rifle or, if the kids or wife are around, you may want to mix up some JB Weld or Fix All, wait until it's almost set and stuff it into hole keeping your finger over it until hard (about 30 seconds). You should rarely, if ever, need to do this. I've refilled 1000's of bottles and only had to shoot two. :)I usually get about 14 full bottles per tank. The adapter paid for itself the first tank.Follow usual precautions about nearness to open flames, sparks, etc, or you will lose your eyebrows or blow yourself up.