These are synthetic waterproofing covers with one side black and the other one is yellow to easily detect puncture, tear and similar situations that may occur in the application. The yellow part, which is a thin layer during production, is equivalent to the other dark part. Only the color is different. In these products, which are generally produced in 2 mm thickness, approximately 0.6 mm of 2 mm is produced in yellow, 1.4 mm in black and dark color. Thus, the PVC membrane provides visual control thanks to the yellow signal layer.