The Airboard is so hot that Hudson Trail Outfitters in Tenleytown had to sell the display model to meet demand on Washington's first snowy day.

No, scratch that. It's the neatest innovation since the snowboard. But it had not sold that fast. The manager lent the only visible Airboard to a magazine writer, who wanted to blitz headfirst down a ski slope on this four-foot inflated pillow before contributing to the burgeoning buzz about Xtreme sledding.

Hype is manufactured as easily as artificial snow, but the Airboard does qualify as a winter sports phenomenon.

"This is the true dynamo in this year's bunch of products," said Sandy Cohan, general manager of Hudson Trail Outfitters. Since his stores began selling them in September, he has reordered four times.

Europeans have been screaming down mountains on Airboards since 2001, when Joe Steiner, a snowboarder grounded by injury, launched his first body board for snow in the Swiss Alps.

"I really wanted to create a new sport," he said from the office of his three-person company, Fun Care, outside Zurich.

More than 12,000 boards have been sold, and race events have been covered on European television. Airboards migrated to the Rockies two years ago and are now allowed at six resorts across the country. On Thanksgiving weekend, West Virginia's Canaan Valley Resort opened the first dedicated terrain park in the country where daredevils can bump, fly, roll and catch big air, as aficionados say.

Cohan estimates about 200 early adopters in this area have paid $269 for an Airboard with bag, repair kit and hand pump, or $149 for a child's version. The inflatables weigh less than six pounds. After pumping up the air chamber, riders flop headfirst, belly down and toes up to trace graceful S-turns or avoid trees.

Control is a significant design feature for those "6 to 66," as Steiner likes to say. At 47, he has given up tricks. But a DVD of the Euro race circuit shows the 18-to-30 crowd has developed a flair for custom moves and plowing into really deep snow.

"Being in the flying position, if you go through the powder, your mouth just moves back to your ears," Steiner said. "It's incredible. Being horizontal, if you do a little jump, you feel it more in the belly -- you feel like you lose the weight of your body."

Steiner spent 10 years developing the Airboard. He was working as a quality control manager for DHL when a snowboard accident tore the tendons in his ankles, he said. Unable to stand for two years, he researched inflatable sleds and patents back to the 1940s, looking for an alternative to skis and boards. He drew inspiration from ocean body boarding, which he had tried.

A Swiss maker of inflatable hospital mattresses helped him through 16 costly prototypes before the aerodynamic shape and runnerlike ridges came together. Urethane plastic solved every design problem -- remaining flexible in extreme cold and withstanding abrasion -- but it was too costly. The final innovation was to reduce the urethane to a thin coating over a less expensive nylon shell. The Airboard is manufactured in Asia.

Unlike tubes or toboggans, the Airboard can carve turns the way skis do. By shifting weight and gripping handholds, riders can perform 90-degree hockey stops.

"Without these rails it would be totally dangerous," Steiner said. "You could not stop or steer."

At last winter's "world series," an Airboarder achieved a recorded speed of 88 mph, according to Ann-Elise Emerson, whose company, Emo-Gear, is the U.S. distributor.

"The freestyle tricks are just beginning," she said. "The kids will define the culture, but people of all ages will ride." Body boarding has its own fashion requirements. Emerson cautioned against "low-riding hip-hop baggies. If you wipe out, you're going to have snow up and down your pants."

Steiner expressed satisfaction that a body board adventure requires less gear and special clothing than a ski outing or a romp on a snowboard.

"You have just a backpack with the board inside," he said. "If you're on the slope, you have this inflated bench you can also sit on. We believe there has never been a more comfortable sport."

Mad River Rocket of Warren, Vt., also offers a controllable downhill experience, on a polyethylene sled.

The designer, Dave Sellers, an architect who taught at Yale, wanted "a way to slide down a hill and not crash into a tree." A little more than five years ago, he devised a sled with a negative keel to create a "monorail" of snow for control. Riders perch upright on knee pads, like canoeists wearing seat belts. They carve turns by shifting weight from side to side.

Mad River Rocket says it sells 5,000 to 6,000 sleds a year. A flame-red Stinger costs $53; a Killer B with deeper channels costs $85.

Sellers recommends taking the Mad River Rocket into the backcountry on snowshoes.

"I feel proud of the fact that you don't need a machine, a groomer, an instructor," he said. "You never would have to have a teacher. There are no lift tickets. A lifetime pass costs $85." He waxes on about "no condos, no snowmaking, no parking lots," just zigzagging through the snowy woods.

An estimated 18 million people engaged in traditional snow sports last winter, according to SnowSports Industries America. But the number of alpine skiers declined from 10.6 million in 1994 to 5.9 million last year, according to the National Sporting Goods Association. The once-renegade sport of snowboarding, however, grew to 6.6 million enthusiasts last year.

Whether snow body boards or high-performance sleds offer a similar growth opportunity is not yet clear.

"Part of becoming a snowboarder was going against the grain," Emerson said. "We are going to have a bit of that. We are definitely against the grain."

So far, Airboard inventor Steiner doesn't feel chased by imitators.

"I think maybe they are not yet believing in this," he said. "Some companies are still waiting to see what happens. They are not exactly sure that it is going to be the next new trend."

On this day in Tenleytown, a salesman showed off two slim gray boxes, smaller and no heavier than a laptop. The manager figured, with yesterday's snowfall, they wouldn't last long. That used Airboard already was looking like the Lone Demo.

Big Air! The Airboard -- $269 for the adult model, $149 for children's -- is sweeping the country, one slope at a time.