Is there a visible or audible siren when the Shield alarm goes off?

There is an 85 dB siren built into the SCW Shield hub that will sound when an alarm is triggered. You can purchase additional wireless sirens.

85 dB is very loud. it is about as loud as riding a motorcycle or listening to a Boeing 737 fly overhead when landing. It will cause hearing damage if listened to for about 8 hours. You won't miss it.