This little  Ultrasonic Essential Oil Whale Diffuser is compact enough for use when traveling. It will diffuse any pure essential oils or essential oil blends, though it will function best with the lighter oils. Power with two AAA batteries or through your computers USB port.
 
Capacity: 25ml
Dimensions - 5 1/2 x 3 5/16 x 2 1/4 in
Weight: 5.6 oz