The Lumenok (lighted arrow nock) is fast becoming the most popular lighted nock on the market. The Lumenok is a lighted uni-nock and adds only 22 grains of weight to your arrow . Simply remove your nock and put in the Lumenok and your ready to go. The Lumen ok will work with any aluminum arrow that uses the Super Uni bushing and almost all popular brands of carbon arrows such as Carbon Express, Carbon Vision, Epsilon, Easton Evolution, Beman ICS, Beman Matrix, Gold Tip, etc. The Lumenok comes on when shot from your bow and stays on until you turn it off. The Lumenoks 3volt lithium battery has a 5 year shelf life and will stay lit continuously for 40 hours. They work great for hunting and target shooting . The Lumenok also aids the archer with bow tuning .You can see erratic arrow flight much better because of the light on the end of the arrow. The Lumenok is the lightest and easiest to use lighted arrow nock on the market, we guarantee it! Get yourself some Lumenoks today at Skalak Outdoors Groundblind.com SHIPPING NOTICE: These will be shipped Via USPS Priority Mail if ordered by themselves. Shipping cost to you will be adjusted to actual cost. Please do not pay attention to the higher UPS shipping rates you see during Chekout.