Typically, wide primary tubes offer the best gains in power and torque at higher engine speeds, while narrow tubes offer the best gains at lower speeds. (en.wikipedia.org)
Passing a thin, narrow tube with a magnification device inside the body is called endoscopy, and the instrument is an endoscope. (1800petmeds.com)
ONCE upon a time, there was an unconventional US entrepreneur who devised a revolutionary mode of transport that would send people hurtling through narrow tubes at high speeds. (newscientist.com)