All ankle monitoring services are waterproof and are capable of withstanding high levels of water pressure. This allows for them to always be worn, even when the person is bathing. They also need to be charged for an average of 2 hours each day. Most ankle monitors used in house arrest cases are now equipped with a global positioning system (GPS), meaning that the wearer’s location is always known. Some monitoring devices are also equipped with alcohol detection technology called SCRAM. Newer GPS ankle monitoring services have microphones and electronic surveillance capabilities as well, but it is extremely rare to find them used as recording devices.