On md-hunter its says that Garrett has added a ( i ) after each number. At first look without firing it up you can't see the difference. It's all in the new software in more ways than one  If you want to learn more I'll let you go look for yourself.  The only dealings I've had with Garrett Ace was when I got the 200 for my Grandson. I was surprise to see what the Ace 200 had to offer for the money.  More new for 2016.  Chuck