Not a GLV pro but I know a little about a little with electronics. Having both the resisted and unresisted caps would just give you the option to run a standard GLV in the following ways; 3.7v, 5v, and 6+ish volts, depending on the batteries that you use. Assuming that you also had a few different tubes, i.e. the standard, mini, and supermini you would have even more options. You would only need both caps when using the standard tube. Having the resisted cap allows you to use two 3.7 batteries in series so you only have to buy one type of batteries. I think. I am not sure on the actual demensions of the tube but I know that there are mods that stack two 3.7 batteries and then use a variable regulator to control the actual throughput voltage. Obviously if you have two 3.7v bats stacked on the standard cap you'd be pushing 7.4v and that's not the best place to have an atty or carto. Hope this cleared things up a bit.