I'm looking to downsize my rig. I purchased a Genz Benz ShuttleMax 9.2, and I was thinking about two Bergantino 112s. I noticed in the classified section that there are many letter options for Bergantino. They include: AE, HD, HT, NV, EX, IP and HS. The Bergantino website currently shows HD and NV only. Would you guys please explain the Bergantino Alphabet Soup?