This is not a rock-hard, acrylic or thin, clear plastic material. Our semi-flexible, custom made-and-designed, Armor Guard Professional Dental Day-and-Night Guards come in 2 different materials of your choice. First is our flexible, soft EVA material ( default picture shown ) that is recommended for light-to-moderate grinding and clenching with no TMJ symptoms. It is also for those who prefer a softer, cushion feel when they grind or clench. Our second material is flexible yet semi-hard. It is designed to offer teeth protection for moderate-to-heavy grinders or clenchers with multi-symptoms. It will help relieve symptoms like headaches soreness in the jaw muscles, ear, or neck and other jaw issues. It is an extremely durable, dense, hard-yet-flexible EVA material. Our soft material (shown above in the default picture) comes in a clear color with a standard 3 mm thickness for comfort and durability. We also offer a 2 mm and 2.5 mm thickness for users that prefer a thinner material. Our semi-hard material is cloudy in color and offers your choice of thickness in 2 mm, 2.5 mm, or 3 mm. Our semi-hard material will retain your teeth. If you have a previous stone mold from your dentist, you can send us your mold instead of making a teeth impression. The Pro-form logo on our semi-hard material is for demonstration only. Armor Guard is proud to provide exceptional customer service throughout the customization process to help ensure that youre 100% satisfied. Please note that sometimes just like at the dentist final adjustments may be necessary once you receive your final product. Our products are friendly adjustable once you receive them if needed, unlike an acrylic or plastic mouth guard. We expect all of our customers to work with us to resolve any impression or fitting issues that may arise since you are the one making your teeth impression. Working well together will help ensure you receive a perfect mouth guard.