How It's Made simplify overdubbing in different languages. For example, the show currently avoids showing a narrator or onscreen host, does not often have employees of featured companies speak on camera, and keeps human interaction with the manufacturing process to a bare minimum. An off-screen narrator explains each process, often with humorous puns. Each half-hour show usually has three or four main segments, with each product getting a demonstration of approximately five minutes; exceptions are allowed in the allotted time for more complex products. Usually, every show has at least one product with a historic background note preceding it, showing how and where
Whiskers to around 50 mm in (laboratory) rats, 30 mm in (laboratory) mice, and a slightly larger number of microvibrissae. Thus, an estimate for the total number of sensory nerve cells serving the mystacial vibrissal array on the face of a rat or mouse might be 25,000. Rats and mice are considered to be "whisker specialists", but marine mammals may make even greater investment in their vibrissal sensory system. Seal whiskers, which are similarly arrayed across the mystacial region, are each served by around 10 times as many nerve fibres as those in rats and mice, so that the total number