There are two major types of electronic monitoring devices. Both require participants to wear bracelet-like devices. One type is the random-calling device that requires offenders on the program to verify random computer-generated telephone calls with the electronic bracelet device. The other type, the continuous signaling device, monitors the inmate continually by radio frequency. In Fairfax County, Virginia, one of the earliest agencies to explore electronic monitoring, both random-calling and radio- frequency systems were tested for over a year; the random-calling method proved to be more reliable than the continuous signaling. The Monmouth County Sheriff's Office (Minnesota) Work/Wristlet Program combines the elements of work release and electronic monitoring. Under this program, the offender is home in the evenings and on weekends under electronic monitoring; this eases the strain on family life. It is a low-cost program and frees jail space for serious offenders. It also provides "free" services for community projects. Overall, the county saves approximately $500,000 per year compared to incarceration. Nationally, the results of electronic monitoring have been promising.