Although it is a resin horn, it is about 6 mm thick and the accuracy of the adapter mounting part is good, so it was a more solid product than I had imagined. However, there is some wavy distortion in the opening on the driver side, and if you attach an adapter, a step of about 2 mm will be created. It's a good product, so I think it's a little regrettable.
Good product, price and service!