Ryan Howard wears one. So does Jimmy Rollins. And Cliff Lee was rocking one when he pitched his masterpiece in Game 1.

Those choker-style necklaces they've added to their standard-issue red and white pinstripes aren't just any old accessory.

Could it be that accessorizing has pumped up their mojo this season?

The necklaces are specially treated Aqua-Titanium that, according to the Major League Baseball Web site, has the ability to regulate the body's natural electric currents and helps with muscle relaxation, pain relief, and fatigue. All this, the site says, prevents injury.

The necklaces apparently have plenty of believers - or, at least, admirers. Dozens of major-league players have been wearing them this year. And they've become even more noticed in the World Series as both teams' star players have them.

The specially treated titanium is the brainchild of Yoshihiro Hirata, CEO of Phiten, a 20-year-old company based in Japan. Hirata started out making the titanium as beads.

The necklaces are worn in Europe and Japan by professional athletes, from marathon runners to tennis players. Several years ago, a group of American baseball players who were in Japan noticed Japanese athletes sporting the necklaces.

"The players brought the necklaces home with them," said Scott McDonald, a spokesman for Phiten, "and the trend started from there."

Two years ago, Major League Baseball entered into a licensing agreement with Phiten, McDonald said. Each of the 30 major-league teams has color-coordinated versions of the necklaces (available for $39.99 at www.MLB.com). Phiten also makes T-shirts, bracelets, socks, wristbands, and lotions.

The idea of using metals to cure ailments goes back to ancient times. The belief that titanium regulates energy is like the notion that copper eases arthritis.

But while some players report that the necklaces make them feel stronger, more relaxed, and a little less stressed-out, doctors aren't quick to give a thumbs-up. In other words, don't think wearing one will make you pitch like Cliff Lee.

"It seems like what these necklaces do is work on the placebo effect more than anything else," said Mark A. Testaiuti, a spinal neurosurgeon with Coastal Spine, in Mount Laurel and Washington Township.

"We may subconsciously feel an improvement, but that is more based on our expectations than what the devices have been scientifically proved to do for us."