This is an accessory for the ArttyStation OPERA-07 Horizontal Paint Shelf and the ArttyStation Symphony. Open type universal paint board is compatible with all types of paint bottle. Includes 1 set of 4 shelf inserts. Made of high-density MDF, more durable than general MDF. All MDF material being used for Arttystation is coated on both sides with clear, or white for convenient cleaning on general stains with water or special cleaners for the stain. But due to characteristics of the material, it may deform if it is exposed to humidity for extended time or high moisture, so please, keep in mind when cleaning. Assembly required. Recommended to use Loctite 401 Super Glue or Gorilla Wood Glue for assembly.