The EAX-300 Door Prop Alarm from Detex Corporation of New Braunfels, Texas, assures that doors left open by mistake or intent won’t defeat the whole security system. The alarm can be field-set for door-prop times ranging from one second to four minutes, with a 15-second default. After the time is up, a 100-decibel alarm sounds; when the door is closed, the alarm is silenced, so there is no need to wait for a keyholder to disable the alarm. The alarm is powered by a 9-volt battery and has a low-battery LED alert. It can work in conjunction with the company’s lockdown and tailgate detection systems, and it is available in a weatherized version.