Description: - 4mm(0.15inch) thickness tempered glass - Overall Outer Diameter: 21cm - Easy "click-in" construction - Casted and polished 316 stainless steel accessories - Strong ABS Molded Design, Anti-Aging, Anti-Corrosive, Ultraviolet Resistant. Specification: 1. Round shape porthole for Boat/Yacht/RV/Industry Cars 2. Corrosion free synthetic fittings and durable water-tight rubber seals 3. Temper Glass for Strength, Clarity, and Chemical Resistance 4. The two fittings can be loosened to allow you to swing open the porthole 5. Easy to install, pre-drilled countersunk fastening holes (screws not included) Package Includes: 1 Piece Porthole.