Brass Material Camping Outdoor Gas Cylinder Propane Filling Adapter/Adapter Cylinder Tank Coupler Tools for Camping* Made of high quality materials, durable* Female cylinder thread x soft nose P.O.L. For personal use.* Fills 1lb. Bottles in 1 minute or less as fast.* Works with all 20, 30, or 40 lb 50, cylinders.* With this adapter, you are not able to fill the smaller bottles that it will only put in the tank as much as it can hold, you can also refill the larger tank if you find yourself in a situation where your larger tank will dry out.* Connect the smaller cylinder with this adapter and equalize the pressure between the two tanks.* Compared to the others, Ours has a safety function. When the flow capacity is too high, ours will automatically close at the end. This feature controls the propane transfer capacity and ensures that the tank never overflows. This protects you from dangerous filling of the tank when there are none.* Tip Handle:1, connect the left threaded adapter handle to the tank, connect the right threaded adapter cap to the 1 LB cylinder (tighten by hand)* Turn the 1 LB cylinder and tank upside down* Open the valve on the tank for a few minutes until you hear propane transfer. Then turn the valve off.* Return the 1 LB cylinder and tank to the upright position.* Disconnect the smaller 1 LB cylinder first.*