Pebble Diffuser Despite its small size, the Pebble Diffuser packs a lot of power. This ultrasonic diffuser offers several effective features, including a five-hour continuous runtime, 10-hour intermittent runtime, and multiple light settings. The Pebble Diffuser’s size also makes it a subtle addition to your home décor, while still allowing you to enjoy the aromas of all your favorite essential oils. Primary Benefits Water capacity: 100 mL / 3.5 fluid ounces Suggested room size: up to 270 square feet / 25 square meters Continuous operation: up to 5 hours Intermittent operation (5 minutes on and 5 off): up to 10 hours Timer: 2, 5, and 10 hours Cyan, white, purple, warm white, and blue light options