SHELTON, Conn.—The complete tour of Wiffle Ball Inc.'s one and only factory takes about 20 minutes. And that is with all the technical details left in.

The top floor of the two-story cinderblock building off Connecticut's Route 8 is devoted to packing and storage. The ground floor has an aging wood-paneled office with five desks. And in the next room lies the heart of the 15-employee operation, where two injection-molding machines hum along to produce thousands of Wiffle Balls every day.

The Wiffle Ball mystique has been entertaining hundreds of backyard, summertime players for many years now. (Originally published on 7/3/08)

In fact, every single Wiffle Ball that will sail across backyards this summer was produced here. Just like every single Wiffle Ball that has sailed across backyards since the factory opened in 1959.

"You've got to stick with what works," said Stephen Mullany who, along with his brother, David J. Mullany, runs the company that their grandfather started in 1953.

That philosophy is how three generations of the Mullany family have built a company—and kept it thriving—around a single, unchanging product. The ball has always been white plastic. It has always had eight holes. These facts are immutable.

The Making of an Iconic Ball

Wiffle Ball has hardly ever felt the pressing need to diversify its line. At various points, they have tried flying discs, plastic golf balls, and even silk ties with pictures of Wiffle Balls on them. But each time, they were reminded that people did not have much use for anything beside the bat and ball.

"What do you need? You need a Wiffle Ball, a bat, and another kid to play with," said David J. Mullany. "And really that's it."

Their product is so iconic that a few years ago, the Mullanys trademarked the bright yellow color of their bats, much the same way Tiffany & Co. protects the particular shade of blue on its jewelry boxes. It means that no one else can manufacture a plastic bat in the Wiffle Ball color.

Even today, the Mullanys are still surprised by Wiffle Ball's cultural traction, especially considering that the company has not advertised in half a century. (Their one and only television ad starred Whitey Ford.)

Stephen Mullany at work where boxes of bats and Wiffle Balls are stored for shipment. Mustafah Abdulaziz for The Wall Street Journal

Playboy magazine once dubbed Wiffle Ball one of the "classic" American brands alongside the likes of Zippo lighters and Monopoly. In 2005, a Wiffle Ball and bat made the cover of Sports Illustrated in the hands of Olympic softball star Jennie Finch. And the following year, one man famously paid $30,000 at a charity auction to play Wiffle Ball with David Ortiz.

Better yet, Wiffle Ball has had orders from couples who wanted their names printed on balls so they could give them out as party favors—at their wedding.

One dirt track racecar team wanted Wiffle Ball to make them plastic balls with slots on both sides so that they could use them to reduce sloshing in the gas tank. Then someone else wanted them to make balls without any holes so they could use them for flotation on a home-made submarine.

They filled the racing team's order. They turned down the submarine guy.

Clients have found alternative uses for the bats, too. Steven Mullany said that there is a down pillow company that uses them to flatten out pillows. Some peach farmers, who appreciate how light they are, use them to poke at branches and knock out loose fruit.

And the Mullanys know of hog farmers who fill the bats with BB gun pellets and rattle them as they lead the pigs about.

To the Mullanys, running Wiffle Ball's mini-empire—stranger sides included—is a daily reality. But all of this would have been inconceivable to their grandfather, who died in 1990, when he first made his son a toy in 1953.

The Mullanys can reel off the story their grandfather—from his decision to leave the family tobacco farm to his brief career as a Depression-era industrial-league pitcher—at the drop of a hat.

It goes like this. Twenty years after being saved from unemployment by his reputation as a solid left-handed pitcher, David N. Mullany was once again out of work. Except now, it was 1953 and he had a family to feed—a family that saw him leave the house in the morning and come back in the evening and thought he still had a job. What he was actually doing was looking for one and bringing home the money from his cashed-in life insurance policy.

Every single Wiffle Ball that has sailed across backyards was produced in the Shelton, Conn., factory opened in 1959. Mustafah Abdulaziz for The Wall Street Journal

After every fruitless day, he would return to the same scene: his son playing baseball with his buddies in the back yard. Their only care in the world was figuring out how to throw a curve ball.

"He could throw a lazy curve,'' said his son David A., now 70 years old. "And I could never do it."

Right about then, Mullany's life took a crazier turn than any Wiffle Ball. The kids were playing with plastic golf balls that, try as they might, they could not spin. So the two Davids, father and son, began experimenting. They wanted to create a ball that would do the work for them.

Mullany came across half-spheres of plastic that a perfume company was using in promotional packets and thought they might hold the solution. Over the course of a week, they cut all sorts of patterns into them before finally settling on the now familiar one.

"It was good enough to keep the rotten crew that I hung out with busy," said David A., who soon began working in his father's factory taping the wooden bat handles. (Wiffle Ball made skinny wooden bats until 1972 before switching exclusively to plastic.)

A tool bench features different Wiffle Balls with customized logos. Mustafah Abdulaziz for The Wall Street Journal

Since then, aficionados have taken Wiffle Ball far more seriously than the Mullanys could ever have anticipated. The 1,200 YouTube videos on Wiffle Ball pitching alone are proof of that. So are the 200 Wiffle Ball events the company sponsors every year—on the condition that they do not somehow tarnish the brand. ("We ask that you don't have this monster kegger going on," said David J.)

Wiffle Ball connoisseurs follow the company so closely that every few years, when the factory replaces its worn-down molds, the Mullanys have to field a slew of complaints.

People call and tell them the weight of the ball is off, when in fact the crisp new molds are only going back to accurately producing the correct specifications. "It's one or two grams' difference," Steven said, "but people notice."

And, every so often, a scientific paper will land in their Wiffle-Ball-adorned mailbox, claiming to have uncovered the secret behind the ball's aerodynamics. A 2007 study from Lafayette College, for instance, speculated that the ball's acute spin could be attributed to "a trapped vortex flow."

The Mullanys have little interest in finding out. They just know that their Wiffle Ball has ducked and dived for 58 years. And they are not planning on changing a thing.

"Let's not overthink it," David J. said. "It's Wiffle Ball."