I am currently thinking about buying a used Tim and was looking at it - it seems rare to see a OD / Boost pedal with an effect loop. The description of how this works is vague, but I assume it is there so that other pedals, possibly another OD, can be in series between the OD section of the Tim and the Boost section? I was also thinking about other ways this adds versatility to the pedal. For example, I suspect you could run a patch cable from the output to the input of the Tim and plug the guitar into the effect receive, effect send goes to amp, resulting in putting the boost in front of the OD, right? I just thought it was cool how it is two pedals in one and still can be utilized that way because of the loop.