Neptune's website says that the Trident Tester requires "Apex or ApexEL (not Apex Classic, Lite, or Jr.)." My problem is I don't know what Apex classic is? I know what Apex and ApexEL new look like. I don't know if there are multiple generations of Apex that will work. In summary, are they saying that none of the previous generation units will work and you have to have a new style?