That's a large-mesh casting net, with 8 cm mesh size. Is it for carp and crucian carp? Rainbow trout would slip through unless they're over a foot long. The size looks to be about 6 meters in diameter, with the net part about 5 meters long. It's a large one, and quite rare. It's pretty old, but being nylon, it should be okay, although I can't assess its strength. The line is probably size 5 or higher, but please judge the mesh count and other details from the photos. This is being sold as junk, so no returns accepted.