EAS systems involve attaching an item to the articles being protected which sets off an alarm when the articles pass sensors, usually placed at store exits. Systems have various features depending on whether they operate by magnetic, microwave, or radio frequency principles. The most recent EAS Technology developed is the magneto-acoustic system, which uses small tags containing amorphous metal that vibrates like a tuning fork, causing the system to detect only a specific response. The detection rate is high and the false alarm rate is near zero. EAS has been used to prevent the theft of tiny electronic components and to prevent patients from leaving hospital wards without authorization. Some of the factors to consider in selecting an EAS system are the acceptable detection rate, whether the system has full coverage, susceptibility to false alarms, whether the system can be integrated with other security controls, ease of maintenance, the appropriateness of the tag for the types of items to be protected, and whether the tag is reuseable or disposable. The current trend in EAS technology is the merging of EAS systems with other security technologies, such as access control.