Stainless steel and a good quality spice grinder grater thing for nutmeg and similar things. Far better than the cheap aluminum or zinc or lesser quality alloys one finds in most shops or elsewhere online. Definitely good quality stainless, looks like 316 but there's no stainless stamp indicating grade ( so really not sure of the alloy ).I have some old Japanese forged Molybdenum mid century Dion Lucas knives still in use, never rusted and still shiny like new other than wear on the wooden handles and some scuffs from sharpening, normal use and being stored loose in a drawer sometimes. While this grater is made from thinly rolled, stamped and pressed sheet, the quality of the stainless itself is somewhat similar to Mo stainless which is why I think it resembles 316.It's extremely sharp on the grating business end and it grates through nutmeg with ease, smooth as butter, and grates to a fine powder. Handle with care, it's sharp.. This grater is not like other graters on the market of lesser quality and duller grate.The storage compartment is a bit small for a large unground nut. I never use the compartment for storage anyway with this style grater. I keep the grater in a small shallow ceramic or wooden bowl, along with two or three pieces of nutmeg, on the spice shelf or prep table.I've used this type of grater my entire life. This one is better quality than most that are sold these days, and at a good price too, all things considered.Give this one a try. If you know you like this style grater, you'll probably like the performance that this one offers; super sharp and grates to fine dust and powder.