To be eligible for intensive supervision with electronic monitoring, the offender must have a prison sentence that does not exceed 2 months, have a stable and suitable residence equipped with electricity and a telephone, and be willing and able to work. The offender wears a small transmitter on a strap around the leg or ankle. The transmitter automatically sends frequent signals to a receiver that is connected to the home telephone and electric power supply. The receiver registers the signals and forwards them to a central host computer for comparison with that offender's plan of activities and times. A breathalyzer apparatus can be attached to the transmitter to test for alcohol use. In addition to electronic monitoring, the probation service uses other forms of control, the nature and intensity of which are determined in relation to individual circumstances. Approximately 3,000 offenders participate in intensive supervision annually. If intensive supervision can be used on a sufficiently wide scale, it should be considerably cheaper than imprisonment. Statistics show that in addition to fulfilling the control requirements, most of the offenders have participated in a number of positive activities that are likely to improve their adjustment in society.