AQP - Acquedotto pugliese - the water organisation of the Puglia region FOGNATURA - Sewage
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 similar to another lid made by the same manufacturer, and differs mainly in the way the consumer’s name appears