Titanium: 1. Material-exceptionally lightweight and durable metal material. 2. Comfort-They are corrosion-resistant and hypoallergenic, making them an excellent choice for those with metal allergies. 3. Durability- Titanium frames can be thin and elegant while still providing strength. 4. Monel: nickel-copper alloy commonly. Monel frames are corrosion-resistant and durable, but they may contain nickel, which can be a concern for individuals with nickel allergies. 5. Aluminium: Aluminium frames are lightweight and corrosion-resistant. They are often chosen for their modern and sporty designs. However, aluminium frames may be less durable than some other metal options. 6. Flexon (Memory Metal): Flexon is a brand of memory metal, which is a titanium-based alloy that has the unique ability to return to its original shape even after being bent or twisted. Flexon frames are known for their flexibility and resilience.