It is usually mounted vertically and doubles as a grip much like an expansion chamber. There may also be a regulator onboard the gun, for example, the Automag. If you use a nitrogen system a secondary ASA regulator is often used to keep pressure fluctuations at a minimum. A gun such as the Automag with an onboard regulator usually doesn't need another regulator besides the onboard nitrogen reg. This hose takes the CO2 bottle or Nitrogen system off the marker to lighten the gun and if using CO2 it will give the gas time to expand.
Remotes can range from a simple steel braided hose to coiled hosing.
The usefulness of sights on paintball guns is debatable because, unlike a rifle, many markers will not always put the ball where you want it to go. Squeegees - When a ball breaks inside the barrel it will greatly reduce the performance of your gun. Squeegees will clean the barrel out. Stock - Stock has many meanings in paintball.