Effective this weekend, drivers in the Winston Cup, Busch and Craftsman Truck series must wear either a HANS or Hutchens device at any time they are on the track during a NASCAR-sanctioned event.

NASCAR has encouraged drivers to wear a restraint system this season, but had declined to make them mandatory before Wednesday. On a regular basis, 42 of the 43 Winston Cup drivers voluntarily wear one of the two devices.

"The driving force for the mandate was the level of comfort among the teams and drivers in wearing the devices," NASCAR vice president George Pyne said. "Initially, we didn't feel it was appropriate or the right thing to do to make our drivers feel less safe.

"But NASCAR has worked closely with safety experts, drivers and manufacturers to address issues that led some drivers to feel that these devices might make them less safe. As time has gone on and teams have grown more comfortable with them, we felt it was the right thing to do."

Jeff Gordon, the three-time series champion and current points leader, applauded the decision. Gordon, who wears a HANS device, said he had been uncomfortable until now about NASCAR making restraints mandatory.

"It took me time to get comfortable to wearing the device and also understand the way it works," Gordon said. "I do think that it is now the right time. I am a true, true believer in them."

NASCAR said nine drivers did not wear any type of device during Monday's race at Martinsville Speedway, a short track where speeds are much slower and some competitors feel the danger is lower. But Tony Stewart is the only driver who has regularly declined to wear a a head-and-neck restraint at any track.

While the head-and-neck restraints are required in some open-wheel series, NASCAR never has forced the use of any such safety device.

But the sanctioning body had been under increased pressure to do so since the death of Earnhardt, a seven-time series champion, at the season-opening Daytona 500.

Earnhardt died of a skull fracture, the same thing that killed NASCAR drivers Adam Petty, Kenny Irwin and most recently Blaise Alexander, a 25-year-old ARCA driver who died earlier this month in a wreck in Concord, N.C.

Many experts believe the skull fractures could have been prevented by the use of a restraint system. But NASCAR hesitated to require them based on a reluctance from drivers to use them and lingering questions about their effectiveness.

Pyne said further studies, educational seminars for drivers and changes to the cars -- like the widening of the drivers' side window to make an escape with a HANS device easier -- made the requirement possible.

"The willingness of the manufacturers to work with drivers in addressing potential drawbacks and explaining benefits also has allayed drivers' concerns," Pyne said.

The decision came just two days before the Winston Cup series heads to Talladega, one of the fastest and most dangerous tracks on the circuit. But Pyne played down the timing of the announcement, instead saying that the already overwhelming use of the devices played heavily in NASCAR's decision.

He also said the sanctioning body waited to mandate them until the competitors were comfortable with them.

"I think when you are talking about a device that restrains the motion of someone's head who is running at 185 mph, that not only impacts the safety of the driver but everyone else around them," Pyne said. "If a device made a driver feel less safe ... we don't feel that is a safe environment.

"But since most of the drivers have been able to work with the devices, it no longer was an issue."

The head-and-neck mandate was one of several safety issues addressed by NASCAR, which also said: