They are all pretty much the same. I'm 90% positive the v1, v2, and v3 all share the same dual diaphragm design. The front housing is removable which lets you change the insert. There are three different types iirc. Stock, purple, and gold. You can also run it with no fitting installed. The v1's have smooth housings, the v2 and v3 have the little faux heat sink grooves in the housing. V2 came in "limited edition black" and v3 has a holographic hks logo. Gotta catch em all!