Marine Grade Polymer (MGP) is a high density, durable polyethylene material. It will not rot, warp, splinter or, swell when it is exposed to the weathering conditions of high humidity, wind, salt water and the extreme UV rays of the Hawaiian sun. The color is inherent, it is non-porous and it will not chemically breakdown with exposure to chlorine or salt water…no rust, no mildew and no more peeling of painted/powder coated metals.

Environmentally friendly and 100% recyclable. Easy to clean and virtually maintenance free. Automotive silicone polishes or household furniture polish can help to hide any scratches that my occur.
An excellent product for usage exposed to salt water.

Here is more information straight from the manufacturer:

Our Marine Grade Polymer is a high-tech material that has been used for more than 25 years by shipbuilders on the topsides of sailing and motor yachts. Besides its extreme durability, this high density polyethylene is significant because it contains more than 30 percent recycled resin. It is also recyclable as Category 2 HDPE – High Density Polyethylene. Additionally, the raw materials, equipment and manufacturing processes emit no harmful gases or byproducts into the atmosphere, and all material waste is recycled back into the original product. Aside from its Green advantages, this marine grade polymer material provides a number of substantial benefits to consumers. It has zero porosity and will not absorb water, and will not crack, rot or separate in any outdoor environment. It also presents no fire hazard and is resistant to most chemicals. And because the color pigment is all through the material, a slightly scratched surface is less noticeable.

Originally engineered for the Marine industry, this nonporous material is a perfect fit for salt water climates that typically corrode and weaken metal furnishings through years of exposure. Additionally, furniture crafted from this strong, heavy material resists winds that routinely move and damage lighter furniture. Telescope Casual only uses 100% Genuine Marine Grade Polymer to ensure that their furniture meets strict quality standards.

Telescope products made with MGP have won ICFA Design Excellence awards in 2008, 2010, 2012 and 2017.