Vertical Adapter (where you screw your gas-thru, expansion chamber or regulator into):
The ASA (Air Source Adapter) is where you screw your tank into.
Detents I would suggest Kila Products magnetic detents.
Feedneck CCM or New Designz Pro Lock.
Barrel, Smart Parts, J&J, Dye, Stiffi, CP, there are a ton of great barrels out there. More important than the barrel is matching it to the correct paint.
Check out www.ottersccustoms.com
everything you could ever want or need to know about Spyders is on there.