Item Details.. Item detail fields are the per-category ( or global ) attributes a seller fills in when listing — things like Brand, Year, Size, Color, Mileage, Edition, etc. They're defined per category (or global) , so a Trading Card listing might ask for Year, Set, Grade, Population while a Vehicle listing asks for Year, Make, Model, Mileage, VIN. As a buyer, they show up in the item details panel on the auction page and are also filterable on the browse page, so you can narrow results to "1986 / PSA 9 / under $500" without trawling through every listing.