The best wired door and window alarm contact depends on the type of installation that the sensor will be used in. Each hardwired contact will work better in certain installations than in others. Choosing the best sensor for the situation is vital for achieving the best possible end result. Hardwired door and window contacts typically all work in the same manner. These devices include both a sensor and magnet. The sensor is placed on or inside the frame of the door or window. The magnet is placed on or inside the door or window itself. When the door or window is opened, the magnet will become separated from the sensor. This will activate the internal reed switch inside the sensor. When this happens, the sensor will tell the security system that the zone has been faulted. For any hardwired sensor, a wire will need to be run from the sensor either to the security panel, expansion module, or to a wired to wireless converter. A good starting point when deciding on a hardwired sensor is to determine where the sensor is going to be placed. For example, a sensor used in a commercial setting or on a garage door may allow for a greater gap between the sensor and magnet before the internal reed switch activates. Some great hardwired commercial contacts include the Honeywell 960 and the Honeywell 968XTP. Commercial contacts from Honeywell's XTP line are also great for outdoor use. It should also be mentioned that commercial contacts are typically surface-mounted. However, unlike residential surface-mounted sensors, commercial sensors can typically have a wider gap between the sensor and magnet. If the sensor is going to be used in a non-commercial setting, the user must decide whether the sensor will be surface-mounted or recessed. A surface-mounted sensor is placed on the outside of the door or window frame. Its corresponding magnet is placed on the outside of the door or window itself, within about half an inch of the sensor. This makes the installation as easy as possible. However, some users may not like the fact that the sensor will be visible on the door or window. Some great hardwired surface-mounted sensors are the Honeywell 949 and the Honeywell 940. On the other hand, recessed sensors and their magnets are inserted into holes that are drilled into both the door or window frame and the door or window itself. This will prevent the device from being seen on the outside of the door or window. However, the installation may be a little more difficult, since holes will need to be drilled into the door or window and its frame. Some excellent hardwired recessed sensors include the Honeywell 951WG and the Honeywell 944T.