'Concentrate' and 'essential oils' are TV code for hash oil. Occasionally they'll split hairs a bit to put the solid hashes into the LL Cera but basically the older stuff was set up for oils, herb/bubble or 'e-juice'. They did a LOT of e-cig business before ever entering THC systems, tobacco smoking cessation is the founding goal of the company. Ava is just a juice rig. Ultra and Ultra max are battery bodies. Revolution/DART, Evolutionand the other products were added to the Ultra series (there are actually 3, based on 10440, 15500 and 17670 size batteries.
Originally the biggest Ultra used two RCR123As (3.0 Volts each) for "Standard Voltage" of 6 Volts. T1 (first herb vape) used this, following products adapted into the line. Lower power carts, like Revolution/DART can also be had "Low Voltage" marked with a LV on the bottom, 3.7 Volts using one batter rather than two. SV versions tend to heat a bit faster although need more battery charging.
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