SAFETY - Built in safety feature that will ensure you never over-fill your smaller tank. Well-constructed, built Heavier, Bigger, and Safer.Cuts off gas flow automatically when pressure is reached (rubber ring allows for proper seal) EASY INSTALL - No others tools required and easy to install with handheel grip for tightening. CORROSION RESISTANT - 100% solid brass construction provides secure and airtight connection for your security GREAT FOR - Camping, tailgating, heating needs,cooking outdoor and much more. Running out of fuel from a 1lb propane tank will not be a problem anymore, this adapter could refill your 16oz 1lb propane tanks with larger propane tanks. REFILL EASILLY - Fits all refillable green 1 lb propane grill cylinder bottles and fill easily and quickly. INSTRUCTIONS: **CAUTION** Due to the highly flammable gases, you MUST be outdoors to refill your 1 lb cylinder tank. Stay clear of flames and sparks. For maximum filling, place your cylinder tank in the freezer for up to 30 mins before filling it. Put your empty 1 lb cylinders in a freezer for a couple of hours. Attach the coupler to your 5lb to 50 lb propane tank. Attach your 1 lb. tank (fresh from the freezer) to the adapter. Pick up your large tank and turn it upside down and rest it securely on the corner of your picnic table. Open the propane valve and shut it off when the flow of liquid propane stops. Turn everything right side up and remove the 1 lb. cylinder. Repeat as necessary. NOTE: You need to turn your bulk tank upside down so liquid flows out of it. You need to chill your empty tanks so that there is a lower vapor pressure in the empty tank than the bulk tank. Your refilled tanks will not be totally full, but this is good because over filling can cause them to vent gas if left in a hot place.