C.M.C - Câmara Municipal de Cascais - Cascais Municipality PLUVIAIS - Rainwater
GS - Spheroidal graphite cast iron - a special cast iron in which the crystallization of carbon has been slowed down, which makes it close to steel - also called ductile iron (Thanks to Vuori Susi for the clarification)
The lid is almost identical to another lid, and differs in several details, including standard markings, the way the manufacturers logo is displayed, and more Click for cover's details