This is the Mares JAX Custom Fit Mouthpiece Reduces Jaw Fatigue - Molds To Your Mouth Features: Innovative technology from Dental Industry Custom Mold Fit Mouthpiece Mold by immersing the JAX Mouthpiece in Boiling Water Bite down to imprint your specific bite Reduces jaw fatigue for a more comfortable dive Available in 4 colors: Standard Black, Translucent Blue or Pink and Clear Reduce jaw fatigue and stay comfortable on your dive!