The extend a Stay can be used for two purposes.
First, if you run out of LP gas in your Motorhome propane Tank, then hook up the extend a stay to an outside LP/propane cylinder. This lets propane gas into your system from the outside cylinder allowing you to have continuous gas supply without having to move your RV and refill your permanent Propane Tank until you are ready to move.
Additionally, you can use lp gas from your Propane system to fuel high pressure appliances. You can fuel high pressure appliances like grills and camp stoves straight from your RVs permanent LP gas system.
The standard kit includes brass tee fitting and 5' flexible pigtail for hooking up outside propane cylinder to fuel your RV LP system. The deluxe kit also includes 12' high pressure appliance hose to fuel your high pressure appliances directly from your RV's LP Gas system. They come 1 kit per package.