Quick links come in all sizes and are very durable and stay tightened well. Here is an assortment, but you can usually find them at the hardware store for a couple of dollars.

http://www.amazon.com/MAXCRAFT-7709-Quick-Assortment-20-Piece/dp/B0042D6HPS%3FSubscriptionId%3DAKIAILSHYYTFIVPWUY6Q%26tag%3Dduckduckgo-d-20%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3DB0042D6HPS