Sirens and strobes are addons to alarms systems that serve several purposes. They scare away intruders, help police in locating the home, office or location that has been compromised and in case of fire, guide people to the nearest available exit. Strobes and sirens go well together because the combination of light and sound is effective in getting people's attention. There are several strobes and sirens to choose from. Strobes come in different volumes and tones while sirens come in different sizes and colors.