Extremely long lasting.Open coat structure prevents loading.Use wet or dry.C-weight paper backing ????????????medium weight, medium flexibility.D-weight paper backing ????????????heavy weight, low flexibility., Resin over resin construction for a strong bond that is resistant to heat and moisture.Box label UPC bar coded for easy identification and inventory maintenance.Our highest quality industrial paper for extra durability on all applications.Broad assortment of grit sizes for a wide range of sanding and finishing applications.