I took a photo of my two fire alarms
Here is the Wheelock I ordered for 45.00
https://www.flickr.com/photos/190305385 ... en-public/
Here is the Edwards Signaling Integrity I bought on Ebay
https://www.flickr.com/photos/190305385 ... en-public/
Here's a video I made of the Integrity doing code 3 I only powered the horn as the power supply I was using can only handle one set of lines for testing purposes https://youtu.be/LqnLmjiJW_Q