Ultrasonic diffusers made specifically for diffusing essential oils should be made with plastic that will not break down when exposed to the volatile essential oil chemical constituents. The Spa Room brand is well known for meeting this qualification. The ultrasonic process helps break oil molecules into smaller particles for more effective absorption and will help the molecules stay in the air longer. This diffuser has a 300 mL (10.10 oz) capacity. It will run up to 8 hrs on high at continuous operation. When running continuously on low it will operate for 9 hours. It has a Light Mode that can be shut off per preference. When on, the light offers a rotating color option or choice of solid color.It also has an automatic safety shut-off.