The rectangular lid consists of 3 triangles, a large triangle, and two small triangles that complete the lid into a rectangle shape.
Note that the triangles that make up the lid are numbered from 1 to 3.
The lid is similar to another lid made by the same manufacturer (in 4 parts)
PT - Portugal Telecom
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)