It's suit madness at the U.S. national championships.

Swimmers are experimenting with _ and sometimes tearing _ various models at $500 a pop. An inspector makes sure everyone is wearing only one suit and it's on a list approved by swimming's world governing body.

Manufacturers' reps are fielding compliments, complaints and questions about the sleek suits that have brought faster times and controversy to the sport.

"This is a very suit-oriented meet," Olympic sprinter Cullen Jones said Thursday.

The favorite query on Hollywood's red carpets _ who are you wearing? _ is a frequently asked question on deck and in the small room where swimmers are required to report before their races. This week, they have to show up a few minutes early so an inspector can double-check that what they're wearing matches the kind of suit they previously said they would race in.

At a glance, an inspector can see a postage-size FINA stamp on the back of suits that have been deemed legal by the sport's governing body.

The inspection is part of USA Swimming's effort to implement FINA's rules on approved suits at its sanctioned events, beginning this week.

Jones is sponsored by Nike, but the company got out of the competitive swimsuit business last year. So he has their permission to try other suits, including those by Arena and Jaked.

"I'm just trying to get the feel right because the last thing I want to think about is the suit," Jones said. "I've busted three suits so far."

Getting into the skintight suits is a challenge in itself, with swimmers needing extra time to dress. They're using plastic bags to slide the material over their feet and donning gloves to ease their hands and arms inside some models. Another pair of hands is needed to zip and unzip them.

"I don't like the rubber suits," said Olympic bronze medal-winning sprinter Cesar Cielo of Brazil, who tried Arena's X-Glide. "I just want to make sure everyone is on the same level as far as equipment. It's the situation we're living in right now."

Aaron Peirsol was wearing the once-banned X-Glide when he reclaimed the 100-meter backstroke world record on Wednesday.

Speedo allows its contracted athletes to wear whatever suit they want while racing, according to Craig Brommers, vice president of marketing.

Allison Schmitt qualified for the world championships this week wearing a Jaked for the first time. She usually wears a Speedo LZR. "I feel like the suits are the same, but I liked really it," she said. "But I really liked the LZR, too."

The various suits have their pros and cons.

Garrett Weber-Gale said he could feel the zipper on his Speedo LZR breaking as he bent on the starting blocks in the 50-meter freestyle heats Thursday.

The Jaked polyurethane suit has caused a buzz because in certain colors it appears quite revealing. It's no longer legal to wear a so-called modesty suit underneath.

"It leaves little to the imagination, but you do feel fast in it," Jones said, smiling.

USA Swimming mandated that manufacturers be in Indianapolis with their approved swimsuits available for all swimmers on a purchase, loan, giveaway or other basis. Because Speedo is a USA Swimming sponsor, it is allowed to set up inside the Indiana University Natatorium.

Other manufacturers are handing out suits from a large white tent behind the building, although reps have been given deck passes.

Speedo brought 1,000 suits to nationals, Brommers said. Superstar Michael Phelps wears various versions of the company's LZR Racer, to which he has unlimited access because of his endorsement deal.

Phelps, like many other swimmers, has grown tired of being asked about suits.

"You can ask me as many times as you like," he said. "I'm here to swim."

This week, swimmers like 2004 Olympian Dana Vollmer and Dagny Knutson, a 17-year-old rising star from North Dakota, have chosen to wear Speedo's LZR, although they aren't under contract.

Then there's Fred Bousquet, the French sprinter who wore a Jaked suit when he set the 50-meter freestyle world record of 20.94 seconds in April. The mark was ratified Thursday by FINA.

Bousquet's Speedo contract ended last year, and he's now signed with Mizuno, the Japanese company that's just getting into high-tech suits. Italian star Frederica Pellegrini has also signed on, and Bousquet said Mizuno wants to expand into Europe.

"It's good and we're still working on it," said Bousquet, who plans to travel to Japan to help refine the suit's technology.

TYR brought 800 suits to nationals, including two Tracer models _ the mostly polyurethane Rise and the mostly neoprene A7, according to team and promotions director Matt Zimmer. Olympians Matt Grevers and Amanda Weir, along with national team member Mary DeScenza, are among its paid endorsers.

The California company has had four other designs rejected by FINA and is asking a French court to appoint an independent legal expert to determine why some similar suits from other manufacturers were approved by FINA and TYR's were not.

"We thought it was wild a year ago when polyurethane started to come out with the LZR and the world records started going down," Zimmer said. "This is a whole new level. It's a very troubled deck."

Last month, FINA approved 202 suits and rejected 10 others for this month's world championships in Rome. FINA put the suits through laboratory tests for thickness, buoyancy and water resistance, and sent back 136 models to manufacturers who were given 30 days to resubmit modified designs.

The United States and Australia have expressed disappointment with FINA's decision to approve modified versions of suits initially rejected for competition.

FINA is in a race of its own to regulate the rapid advances in swimsuit technology that led to 108 world records last year. Some suits are suspected of creating "air trapping" effects that artificially enhance speed.

"Speedo has always felt that the spirit of the sport and the intent of coaches is to avoid buoyancy enhancement as part of swimsuits," Brommers said. "That's why Speedo has chosen not to produce a fully nonpermeable wet suit that will be in effect be banned by FINA as early as 2010."

The world championships are the last major meet of the year. If FINA bans other suits, manufacturers could be stuck with hundreds of thousands of dollars in useless inventory.

Meanwhile, questions, confusion and mistrust are rampant on pool decks around the world.

"FINA put us in a very difficult situation," said Olympic sprinter Dara Torres, who wore a Speedo LZR Thursday. "It's unfortunate they kept going back and forth. You see people wearing these polyurethane suits and you have to wonder, 'Are those fast?'"