Swap fishing flies with fly tyers around the world. A typical swap consisnt of a Swap Meister and 12 fly tyers. Each tyer ties 12 of a given fly pattern and sends to Swap Meister. The Swap Meister (who also ties 12 flies) after recieving all the flies, divids them up and sends one of each tyers back to everyone. You send 12 of your fly in, and recieve 12 different flies back. Details may vary from swap to swap, and are the descretion of the Swap Meister. Fly Swap are often based on various themes (dry flies, wet flies, specific styles or sizes etc.).