Spey shooting heads come in two basic styles. Scandi or Skagit. The most common style are Skagit heads which offer easier learning and allow for effective casting with larger flies and sink tip lines. Scandi heads allow the angler to caster for greater distance because the heads are slightly longer and travel with tighter loops and are more stable in flight. Scandi shooting heads are designed to be utilized with smaller and more lightweight flies.
Most spey lines consist of 3 parts, but it takes a bit more to complete the entire setup from the reel to the fly. The critical parts to get setup correctly are the running line, shooting head, and choosing the right sink tip. Heads can be interchanged using a loop to loop connection that conjoins them to the running lines. This allows you to use one reel and one running line for various heads or weight rods. This is a very cost effective system because you could use one reel and running line for several different spey rods or switch rods.