Technology, lol. The Evans Torque Key might get you in the ball park attaining sort of equal tension on your drums tension rods, but there are reasons that they do not work up to the customers expectations. First of all, the Torque Key really is not a precision piece of equipment, at the selling price how could it be. Secondly and most important, the fitness between each lug and tension rod on the drum is not always a constant. Also, many heads might need a bit more tension on some of their tension rods to get an equal pitch at all the lugs, and this is what to strive for. The Evans Torque Key may get you in the ball park, but you must be able to use your ears to actually get the heads in tune with themselves, the Torque key under most conditions will not do this. I found the numbers on the key are not calibrated but just arbitrary numerals.
I own an Evans Torque Key and I talk from experience. I use it during preliminary set-up of new heads on my Yamaha Maple Custom Absolute kit. The tension rods are very difficult for me to wrap my fingers around when trying to get the rods just touching the hoops of the drums. I have the Torque Key at a very low number that it basically clicks off when the rods come in contact with the hoops, that's all I trust it to do.
I would really recommend getting instructions on how to tune drums by ear, it's not difficult, but takes time and can be a very valuable asset. Being able to effectively tune your kit and maintain it, should go hand in hand with playing it. There are no devices better than one's ears for tuning drums.
Dennis