"These are our alarms that we get if they go somewhere they're not supposed to be," she said as she alternated between offender alarms. "Or if they have a zone and they leave early. We get an alarm if their battery starts getting low."

The TrackerPAL has been used as an electronic leash for gang members.

"They'll put exclusion zones around places that are gang hangouts," Derrick said. "To try to help keep them from getting together."

Olshen said they have tried to make the device tamper-proof. It has a heavy duty plastic strap with steel bands and a fiber-optic line inside that sends an alert to the monitoring center if it is messed with.

An offender can be tracked to within 50 meters, but the technology does have its limits.

"You do run into the limitation of the 'urban canyons.' You're in downtown New York and you're limited in the ability to see three satellites to get a location," Derrick said.

He said it makes it difficult to track, but not impossible. Olshen cautions that TrackerPAL cannot stop someone determined to commit a crime.

"There is no silver bullet. But that's not the majority. The majority are the people who comply," he said.

SecureAlert said the units cost about $400 apiece to make. They are offered to law enforcement agencies for $8 per person, per day. Compare that to the $65 average daily cost to house a person in jail, Olshen points out.

Former astronaut Lisa Nowak, who is accused of plotting to kidnap and kill a woman in a bizarre love triangle, is wearing a TrackerPAL. Olshen told the Deseret Morning News that at one point, he was talking with Paris Hilton's attorneys about equipping the heiress with a new accessory in lieu of jail time. Hilton has been ordered to serve at least 23 days behind bars.

The devices have been used on adult and juvenile probationers, but Olshen said the growth industry is sex offenders.

"A lot of the laws that have been passed are for sex offenders," he said. "The demand for using this technology on sex offenders is huge."

The TrackerPAL has been out for less than a year. A growing number of corrections departments, probation offices and police agencies across the nation are contracting to start using TrackerPAL systems. About 3,000 units are in 35 states scattered across the United States. Several hundred of them are used by the Utah Department of Corrections and the Utah County Sheriff's Office.

The Weber County Sheriff's Office recently acquired one for a probationer who is on home confinement.

"The man we have it on has some serious medical problems. It's hard to keep him in jail," Weber County Sheriff's Capt. Bert Holbrook said.