If you're just stepping into the realm of HPA and are unsure about what you need, this will go over each item and what you'll need to know.
First off, you'll need to do you research. These systems are a little more complicated than you would initially think. Using them safely and maintaining them properly is extremely important because you don't want your shiny and expensive new toy destroying itself in your gun. You'll need to look into the different products from different companies as well. There are some engines and systems that may be better at one thing and worse at another than a different system. We really can't stress doing your research enough!
Once you've found what system your going with, whether it's a Fusion Engine from Polarstar, or a Tippman M4, you'll need to get the required tank, line, and regulator. Tanks are pretty simple as it's just a cylinder that can hold your air. They important things to know about these are capacity and output pressure. Capacity is the volume of the tank (cubic inches) and the pressure it can store the air at (PSI). Let's say we have a tank that is 68/4500. The 68 is the internal volume in cubic inches, while the 4500 is the PSI limit for that tank. Most aluminum tanks have a max PSI of 3000 while carbon fiber and other specialty tanks can hold 4500. Output pressure is the pressure coming out the tank when it is opened. Tanks usually have built in regulators which commonly for airsoft regulate the air to either 300 or 800 PSI. Unless you have a Tippman, those pressures are usually too high for the HPA systems to function, which brings us to regulators.
The regulator brings down the output pressure of the tank to one that the system can use. Most systems can only use up to 130 PSI max and that's really pushing it. Output pressure of the tank can also determine what kind of regulator you need. Tanks that have an 800 PSI output need something that can handle that pressure. The Wolverine Storm, Ninja LPR, and Redline regulators are three examples that will easily handle that pressure. These regulators will also handle 300 PSI tanks easily. Tanks with 300 PSI output pressures (Known as SLP tanks) can take more regulators that can't handle that 800 PSI output (Like the Valken SLP Regulator). Once you've picked your regulator, you most likely have all of what you need for the setup.
Once your system is installed in your gun, you're going to need to tune it. Tuning it with the setup you're going to use is important as other regulators and tanks can affect performance. Some engines such as the Wolverine Inferno and Polarstar F1 use very simple tuning methods as they only have one or two settings you can adjust. The Polarstar Fusion engine is the most tune-able, having multiple settings and even interchangeable nozzles and poppets. Thankfully there are many tutorials and forums about tuning and parts for these systems.
We are very open to questions so if there is anything else you would like to know, you can always give us a call!