There are now a large range of paintball loaders / hoppers available and they vary a lot from basic gravity fed loaders through to fully programmable electronic loaders. The price of loaders varies a lot as well depending on the level of technology you are buying.
Paintball Loader Technologies
The main paintball hopper technologies are sound, break beam and force feed. Sound activated loaders tune into you marker so that when you fire your gun the hopper hears and starts feeding paintballs. The break beam loaders have a magic eye that can see when the paintballs start falling and then starts to feed and the force fed ones keep a constant pressure on the balls so that feeding starts as soon as the balls fall. Right now there s much debate about which is the best technology.
Paintball Hopper feed rates
Paintball hopper feed rates vary a lot from gravity fed loaders that can feed up to about 6 balls per second to super fast electronic loaders that can feed up to 50 balls per second. In practice you need to balance the feed rate of your loader with the fire rate of your marker. Your loader should be able to out perform your marker but not by too much ideally 25% although many hoppers are now adjustable so you can set the desired feed rate.
Paintball Hopper compatibility
Almost all paintball hoppers / loaders are a universal fit and can be swapped from one paintball gun to another. There are however a couple of notable exceptions. The Tippmann A5 and X7 have a cyclone feed system built into the gun and this requires a different style of paintball loader to fit into it. The other exception is the Rip Clip which is available in either BT4 fitting or Tippmann 98 fitting. The Rip Clip is electronic and the same type of loader that fits into the cyclone fits the Rip Clip.
Build Quality of Paintball Markers
The build quality of a paintball gun is again generally related to the quality of the materials used to make it. The higher the grade of materails the more ability the manufacturer has to make high quality parts that will withstand diving and intense tournament paintball play.