This two-window mask is just simply indestructible and is backed by a lifetime warranty against frame breakage. The internal frame, known as the 'subframe' is moulded directly beneath the surface of the silicone rubber skirt which is what gives this mask it's strength and rigidity, as well as eliminating the bulky external plastic frame you may encounter in other masks. The SubFrame features a new and exciting UltraClear lens which delivers exceptional clarity and high light transmission, with no colour distortion, improving visual acuity, especially in low light conditions. A wide field of vision and super comfortable fit complete this functional, stylish and durable dive mask.