This is a steamer. Both the top and bottom sections have outer dimensions of 450mm x 450mm x 125mm. You can fill the bottom section with water and heat it, and then place items like steamed buns in the top section to steam them. The material is stainless steel, and it doesn't stick to a magnet, so it's likely 304 grade. It won't rust. It shows signs of use. Especially the bottom section has warping and stains from years of use. However, it's still usable, so I'm offering it at a bargain price. Please refrain from purchasing if you are overly concerned about condition.