This is a compact sterilizer that easily sterilizes baby bottles with steam in the microwave. - Type: Microwave baby bottle sterilizer - Function: Steam sterilization - Size: Compact size - Sterilization time: Sterilizes in 3 minutes Thank you for looking. I purchased this at Nishimatsuya last year. I used it for a few months, about 2-3 times a week. There are no noticeable stains to the naked eye, but it is a used item. Please note that this item has been stored at home.