Especially with the front ports it depends on hardness and dimensional stability. Therefore, the body of most SUBAL ports of polyacetal resin. With the larger dome ports a seawater resistant light metal alloy is used and the hard coating process subject. When the quality of your underwater photos, the material of the windscreen plays a big role: why all SUBAL flat and dome lenses of glass and perfect optical quality (glass lens) made??. Plano lenses are also coated for optimum light transmission and better contrast performance on the inside.