When posting hardware or materials for sale, it’s important to have as much information as possible. This helps potential buyers as well as sellers!
For machines, this would include brand, model, and condition.
(for example, Ultimaker 2+, light usage over 2 years with 200 hours of print time)
For materials: brand name, size, material type, and condition.
(for example, ColorFabb 2.85mm PETG, still sealed with desiccant)
Asking price and general location should always be included as well.