Perspex sheet 1.2 x 1.8 (North Tonbridge TN10)

This sheet of perspex was bought for a shower liner, but proved impossible to install.
It is about 1.2 x1.8 in size, about 5 mm in thickness, comprising a 3mm perspex layer and a 2 mm opaque white layer. I do not know what the white layer is made from, but it's probably perspex too,