The great abundance of silver, as opposed to the comparative rarity of gold, means that it is less expensive than the yellow metal. The silver bar requires the least amount of processing of all incarnations of the precious metal, therefore asking the lowest premiums added to the spot price. The largest silver bar, the 1,000 ounce Good Delivery bar, is the most economical, being the wholesale unit of exchange. Retail bars are made for investment purposes (and for industrial use – glass coatings, alloys, electronics, etc.) in 100 ounce and 1 kilogram sizes. These carry larger premiums but are still more margin-friendly than coins.