For the most part all models function similarly, however, there are some slight differences between the multiple revisions that have shipped over the last year and a half. For the purposes of this manual we will refer to the original 2 toggle switch models as "rev h/i", the first 3 toggle switch model "rev j" and the latest 3 switch model as "rev k".
Rev h/i is easy to identify since it has only 2 toggle switches.
Rev j and k can be differentiated by the back plate. Rev j uses the large number 5 to finish the date "2015" where as rev k has 2016 where 201 was, but looks otherwise similar. Of course someone could switch a back plate so if you really really want to be sure you can remove the backplate and on the main pcb you will see text "xyz rev X" where X is h, i, j or k.
|Rev h/i - 2 toggle switch (missing "Q" switch)|
|Rev j - 3 toggle switch (has new "Q" switch)|