It will equalize the pressure between two tanks.It is durable and convenient.With this adapter you are not able to overfill the smaller bottles it will only put in the tank as much as it can hold, you are also able to back fill into larger tank if you got in a situation where your larger tank runs dry.How to Mount (For reference only) :Connect left-hand threaded lug of adapter to tank.Connect right-hand threaded cap of adapter to 1 LB. cylinder (hand tighten).Turn 1 LB. cylinder and tank upside down.Open valve on tank for several minutes until you can no longer hear the propane transfer. Then shut valve off.Return 1 LB. cylinder and tank to upright position.Disconnect smaller 1 LB. cylinder FIRST.Inspect 1 LB. cylinder for leaks: Place a small amount of one-half liquid soap one-half water solution on cylinder opening and on relief valve. If bubbles appear, discard smaller cylinder in a safe area.Item Name: Propane Refill adapterFeatures: Durable, Easy to Use, CompactSize: Length: 6cm(Approx.)Colour:brass colorMaterial:brassPackage Contents:2 x Propane Refill adapterOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.