Essix retainers are a type of removable retainer frequently used in orthodontic treatment. They are made from a clear plastic material that fits snugly over the teeth, applying gentle pressure to keep them in place. Essix retainers are often preferred over Hawley retainers because they are more discreet and less noticeable. Additionally, they are generally more comfortable to wear compared to traditional wire retainers and are easier to clean.