A hush comes over the crowd as Don Mattingly strides up to home plate and settles into his familiar batting crouch. But on this day, the bat barely leaves his shoulder. After just a few slow-motion half-swings, the lefty steps out of the batter's box without making contact with a single ball.

In his new role as co-founder of an eponymous sporting goods company, the former American League batting champ is conducting a hitting clinic for about a hundred uniformed little leaguers in a Modell's Sporting Goods store in Milford, Connecticut—so close to Red Sox nation that many of the store's replica jerseys are of Mattingly's old nemeses, popular Boston players. The only hitting today is off a T-ball stand into a net, and is done by a few lucky kids, who weren't alive when the "Hitman" was in his prime. They recognize him for his years as a Yankee coach, helping Joe Torre manage All Stars like Derek Jeter, Alex Rodriguez, and Jason Giambi.

Mattingly, who still has bulging Popeye forearms and looks a little odd in loose-fitting olive-green pants and a black polo instead of pinstripes, patiently critiques each hitters' swing. He gets so wrapped up in giving tips and analyzing prepubescent hitting stances that he almost forgets to mention the bat he is supposed to be hawking.

Branded athletic gear is nothing new; more than a century ago, Pittsburgh Pirates shortstop Honus Wagner signed a deal with Hillerich & Bradsby allowing his signature to be used on their bats. But most are simple endorsement agreements, stamping a name on a product in exchange for cash—Michael Jordan didn't invent Air Jordans. Rarely is a superstar athlete the product designer, or as in this case, company founder and marketer.

"I'm selling a bat that's got a grip on it that teaches kids the right thing," Mattingly says. "I've got something that nobody else has got."

Overall, it's not a bad time for bats. The $216 million bat industry has been steadily increasing over the last few years; manufacturer sales are up 33 percent from 2000 to 2007, according to the Sporting Goods Manufacturers Association. Started in 2006, Mattingly's company now offers wood, aluminum, and composite bats and is in seven of the top 10 big-box retail chains. Sales increased last year by about 1,200 percent (the company won't reveal more specific numbers) and "we're on pace to grow significantly again this year," says C.E.O. Skip Shaw. "There's no question that the overall retail environment is lower this year, but we're still very pleased with our growth."

Traditionally, bat companies have focused their attention on the design of the barrel or on finding lighter, more elastic and durable materials to make the balls go farther and the bats last longer. But the round handle, for the most part, has been left alone.