GEAR4’s Mayfair for the iPhone 7 Plus is a beautifully crafted fine leather case. The D3O inside all GEAR4 BLACK cases is a smart material.  D3O materials in their raw state flow freely when moved slowly, but on shock, lock together to absorb and disperse energy, before instantly returning to their flexible state. This reaction is counter intuitive. The greater the force of the impact, the more the molecules lock together and the greater the protection.