(FORTUNE Magazine) – IT'S LIKE THIS: WE'RE MAMMALS. AS such, we have hair. But somewhere along the line we decided we didn't want all of it, especially the hair on our faces. So someone came up with the idea of shaving, a chore that, on average, consumes 820 hours of a man's life (nearly five solid weeks) and supports an $8.5 billion retail category.

That category has been particularly active over the past decade. You probably remember the fuss when Gillette launched the triple-bladed Mach3 razor in 1998, and with good reason: It had been over a quarter-century since the twin-blade razor had been released in 1971. But the window between innovations--or at least between marketers saying, "Hey, let's get the engineers to slap another blade on that puppy!"--has been shrinking. Five years after the Mach3's debut, Schick introduced the four-bladed Quattro. And early next year, probably in February, Gillette will escalate the industry's arms race by launching the Fusion, the first five-bladed razor.

"It's not about the number of blades; it's never been about the number of blades," insists Michèle Szynal, Gillette's director of brand communications. "It's about the blade spacing, the coating, the angle, the geometry, the spring mounting." Yeah, sure, that's why the Fusion's logo is an oval inscribed with five unmistakably blade-like lines. And why the Mach3 was called, you know, the Mach3. Of course more blades mean more bucks--with a razor plus two cartridges retailing for $13, Gillette hopes Fusion will be a $1 billion brand within three years.

Although Gillette already controls over 70% of the market, the company is treating the Fusion as a high-security project. Instead of providing advance product samples to the media, as it did with the Mach3, it has invited reporters to try the Fusion at a Manhattan hotel suite, with the proviso that the razor not leave the premises. A recent test-drive at one such session found that the Fusion's blade cartridge is about the same size as the Mach3's, but the blades are positioned closer together, creating what Gillette is calling a "shaving surface" (it has actually trademarked the term). And sure enough, the blades really do feel like a composite plane against your face. How's the shave? Very smooth, though it's hard to draw firm conclusions from one use.

The shave with the most mystique, of course, remains the one you get from a barber wielding a straight razor. At the Madison Avenue outpost of the Art of Shaving, a New York--based chain of "barber spas," master barber Ely Mirzahandov is skeptical about the Fusion. "Five blades? It's too much," he says, while administering a single-blade shave that is just as good as the Fusion's. What does he use on his own face each morning? "A straight razor," he says, before sheepishly adding, "unless I'm in a hurry. Then, it's the Mach3."

As you try to wrap your brain around the concept of a five-bladed razor, here's a thought: Gillette's unofficial policy is not to launch a product until its replacement is in development. Can the Gillette Six-Pack be far behind? -- Paul Lukas