The TerraFuse Diffuser features a small water reservoir (65 mL) that covers an area of approximately 322 square feet. It requires no heat or chemicals, allowing the essential oils to retain all of their natural benefits. With continuous and intermittent settings, you have complete control over how long you choose to diffuse, along with the peace of mind knowing that your TerraFuse will automatically shut off when the timer is complete or the water has run out. When used continuously, the diffuser will give you up to four hours of diffusion. The Terrafuse Diffuser is comprised of polypropylene and measures approximately 4″ wide and 5.5″ high.