These Soothing Eye Pillows are 100% cotton and filled with your choice of Lavender flowers, Peppermint Leaves, Rice, or Flaxseed.  Keep in mind that Rice is denser than Flaxseed, so eye pillows filled with Rice or Flax/Rice mix will be heavier than just Flaxseed filled.  For Heat Therapy - You can heat these hot/cold aromatherapy eye pillows in the microwave for 30 seconds to heat it up, then repeat for 15-second increments until you have reached the desired warmth. For Cold Therapy - To cool your eye pillow put it in a ziploc bag in the freezer for at least one hour to have a cold pack or keep one to store in the freezer to use as needed! Eye Pillows are not washable but you can buy a separate eye pillow covers