Series 40 / 42 Description: "Wet" sealed (caulked) system (1/2" wide exposed silicone sealant in the panel joints). System has semi-continuous attachment extrusions and is very easy to install. It is a non-progressive system so that any panel can be removed and replaced at any time without removing any adjacent panels and is typically more economical than the series 20. This system will have the exposed silicone which will collect dirt over time and will need to be maintained and replaced eventually. However, we do offer an option for a cured silicone gasket. See Series 42 details.