How many items are needed and how rare are the they depends on the rarity of the bindle. One bindle is randomly generated each day and it is either common, rare, epic or legendary. Purral, who is the keeper of Purro'Swap, decides which items are needed for exchange.
You can open the bindle right away after the exchange to get one of the products it contains or store it in your inventory. The obtained product is selected randomly. You can also sell bindles in the Market but items received from bindles cannot be sold in the market.