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STI Rex Plus II Electronic Watchdog


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WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov


Choose From Eight Selectable Sounds

As an advanced version of STI's popular electronic watchdog, the STI Rex Plus II offers a versatile way to deter intruders, receive visitor chime alerts, or trigger a siren upon motion detection. Rex Plus II can sense motion through thick doors, walls or glass. When motion is detected, the device sounds one of eight selectable alerts, including an angry, barking watchdog to scare off burglars.

Three Alert Categories

  • Dogs:
    • Dog 1
    • Dog 2
    • Two dogs together
  • Greetings:
    • Ding
    • Ding Dong
    • Chirp
  • Sirens:
    • Siren 1
    • Siren 2

Rex II detects movement up to 26 feet away (adjustable) within 150 degrees. Upon detection, the device begins to produce the alert you have chosen. The closer an intruder gets, the more frequent the barking. With an angry dog barking, intruders are encouraged to leave, and you have time to prepare if they stay. Rex II is also easily muted with a pat on the head.


  • Rex Plus II
  • AC Adapter

We Protect The Things That Protect You®

Safety Technology International (STI) is a family owned and operated business that began over 35 years ago with Jack Taylor's invention of the Stopper Pull Station Protector. STI now markets more than 1,000 products throughout the world that help prevent false fire alarms, theft, and vandalism of the devices that protect us all.


Product Features

Voice Messages/Prompts

  • "Warming up" when power is applied
  • "Armed" after warm up cycle is complete
  • "Growl sound" when unit is muted (for dog sounds only)
  • "Armed" when coming out of mute
  • "Please replace batteries" at power up or after mute button is pressed

Technical Details

  • Manufacturer Part #: ED-55
  • Power Requirements: 120 VAC Plug-in Adapter, 12VDC 0.5A
  • Battery: (optional for portable operation) 6 Alkaline "C" batteries (not supplied)
  • Detector Operating Frequency: 2.4 GHz
  • Power Detecting Standby: 0.15W
  • Power Barking: 6W Peak
  • Battery Life: 90 days maximum with alkaline batteries, depending on the number of activations
  • Detection Range: 26 feet maximum, reduced through obstructions
  • Detection Angle: 150 degrees typical
  • External Output: 3.5mm mono jack, mates with optional STI Lamp Controller STI-30104, supply 75mA at 12VDC for 1 second
  • Weight: 2 pounds, including AC adapter, without batteries
  • Size: 8-1/2(H) x 4-1/2(W) x 5-1/2(D) inches
  • Approvals: FCC, IC
  • Warranty: 90 Day