横山さんの知り合い 4 The product description contains the wording "Material アルミニウム" but judging by the looks it must be some different sort of material. And my suspicion was confirmed when I learned that a magnet may be attached easily. Since the product was advertised as aluminium I expected good heat conduction and easy maintenance similar to cost effective half sheet trays made of aluminium that are commonly available in the US. This is something completely different.