The Gravity fed paintball hopper is the most basic of paintball loaders. There are no fancy electronics or eyes to keep the paintballs feeding into your Tippmann paintball gun. The common problems with these are that the feed rate is based solely on gravity and that the paintballs can jam up easily. To get the paintballs moving again, just give a shake to your paintball gun, which is why gravity fed loaders are commonly referred to shake and bakes.