Here is the product description:The Double Take Archery Halo Nocks Micro Pink are a reliable choice for archers seeking dependable performance. These micro nocks fit arrow IDs of .165"-.166" and come in packs of three. With their patented design, you can rest assured that they won't accidentally turn on when placing on your bowstring. This innovative design also eliminates the risk of a "mini-dry fire" that can occur with other lighted nocks. The Halo Nock is refreshingly simple to use and available in various colors and sizes. Order now and take advantage of fast shipping.Product Features and Specifications: Micro: .165"-.166" Pack: 3