Unless rubbing your nipples is part of your job, anyway.. Andractim testosterone gel is a topical gel, which comes in a tube, containing 80x 25mg doses of DHT. Absorption rate is going to be similar to testosterone gel, or roughly 10%, so youre applying 2.5mgs of pure DHT to your nips every time you use this stuff.
Servos are also used in in-line manufacturing, where high repetition yet precise work is necessary. Of course, you don't have to know how a servo works to use one, but as with most electronics, the more you understand, the more doors open for expanded projects and projects' capabilities.
A Servo is a small device that has an output shaft. This shaft can be positioned to specific angular positions by sending the servo a coded signal. As long as the coded signal exists on the input line, the servo will maintain the angular position of the shaft. As the coded signal changes, the angular position of the shaft changes. In practice, servos are used in radio controlled airplanes to position control surfaces like the elevators and rudders.