TBI PRO Engineering 5 in 1 PEST REPELLER Instruction Manual page 11

Installation
For best result, the Pest Repeller should be positioned in an open area without soft materials or furnitures in
the way for they absorb the ultrasonic waves produced by this product. Ultrasonic waves bounce off materials
as it echoes through the room. As it cascades through the room, it will increase the coverage of the wave.
The electromagnetic waves can go through walls or doors, but we still suggest that doors in the house are
kept open for better effectiveness.
Notice
Do not place 5 in 1 ultrasonic pest repeller on carpeted surface,
behind furniture draperies or other soft objects as they will absorb
the sound waves.
8
Do not use outdoors or let the
unit come in contact with water.