Great home-run hitters tend to have their trademark, the one trait makes their swing instantly recognizable. To find Gary Sheffield's trademark, look at the hands.

They waggle the bat with an almost hypnotic effect -- pointing the bat towards the pitcher one moment, pointing the bat towards the sky the next, then back to the pitcher -- while the rest of his body stands poised to pounce on a pitch. They circle the bat around as he puts his bat in position to strike a ball. Then, if he decides to go after a pitch, the hands whip the bat through the strike zone with such speed that they can make bat not just meet ball, but with enough force to send it on a line over the left-field fence.

"When you watch it," Tigers manager Jim Leyland once said of Sheffield's swing, "it goes through with more bat speed than anybody I've ever seen."

As great an overall athlete as Sheffield has proven to be, as much raw power as his body puts in his swing, his greatness starts with his hands. It's why Sheffield can own one of the most violent swings in baseball, a swing virtually no hitting coach would want to teach to a kid, and remain one of the game's more selective power hitters.

"His contact is like the era of Joe DiMaggio and those guys who didn't strike out much," said Mariners manager Jim Riggleman, who managed Sheffield in San Diego in 1992-93. "Gary hit screaming line drives that turned into home runs and didn't strike out."

There's little to chalk it up to except for God-given ability. However, it helped that he had an eventual Cy Young Award winner for an uncle, and that they grew up playing baseball a few years apart. Hitting against Dwight Gooden, who used his young nephew for practice, helped Sheffield use those hands to hone a quick swing and eventually catch up with Gooden's blazing fastballs. Other times, he developed his hand-eye coordination by learning to hit rocks with a broomstick.

Those quick hands have been a big part of his swing since he arrived in the Majors with the Brewers in 1988, and they've generally stayed true to him over the years. For all hype about his quotes and sound bites over the years, for all the passion he puts into the game, his quick bat has been virtually unquestioned.

Rare was the pitcher who could sneak a fastball by Sheffield. That in itself isn't rare; many of the great hitters could pounce on fastballs in the strike zone. Part of what has set Sheffield apart is the ability to lay off of other pitches, especially off-speed offerings, while focusing on the heater. His bat speed allowed him the extra split second to track a pitch and recognize it before committing whether to swing, and yet still have enough time to turn on a fastball.

That's part of how a slugger can hit 42 home runs in a full season and strike out just 66 times, as Sheffield did in 1996 to join what has been an small group in the expansion era. That's also how a player can approach the 500-homer mark with about 300 more walks than strikeouts.

"He's very aggressive," Leyland said of Sheffield last year, "but he swings hard and puts it in play somehow. A lot of guys can't do that. And he's really good at laying off bad pitches. That's what makes his talent so special."

Even after a broken wrist sidelined him in his final season as a Yankee in 2006, Sheffield's bat speed stayed intact. Not until the last year or so, as shoulder problems took their toll, did his bat speed suffer. As his shoulder ached down the stretch last season, eventually diagnosed as a labrum tear, he had to start his swing sooner to get his bat around.

"If somebody has good velocity or good movement on their fastball, I'd have to try to get out there ahead of it and then be on time," Sheffield said at the time. "When I know I'm right, I don't have to cheat. I don't have to try to make up something in an area that I can't get to. I can just stand up there and wait for my pitch. And when I can't do that, I'm just not the same player."

Finding that player is the key that decides how much further Sheffield can go beyond 500. That swing has been on and off this season, usually in rhythm with the slugger's health, and it's reflected in his stats for the season. Just when his slumps suggest he doesn't have it anymore, there's usually a moment to remind everyone that it's still there.

A.J. Burnett became a victim to one of those moments earlier this month. As he tried to challenge Sheffield on a full count, he left a four-seam fastball over the plate. It came in at 97 mph, but it didn't matter. Sheffield not only turned on it, he sent it on a line into the visitors' bullpen in left-center field at Comerica Park.

Those are the hits that Sheffield's hands allow him, even at age 39. Soon, he'll have about 500 of them.

"His bat speed's fine," Leyland said Sunday. "I think the bat speed's better than it was early on [this season], and I think now it's a matter of centering the ball. I think Sheff can still be a force offensively."