No there is not a small button that turn it on. It has two small wire contacts that are at the base of the nock that activate the light. Before the arrow is shot, the nock is pulled out of the back of the arrow just enough so that the contacts do not touch the shaft. When the bow is fired, the nock gets pushed into the arrow and as a result the contacts touch the back of the arrow and the nock lights up. As far as accuracy, no you will not loose accuracy, however they do weigh more than the standard nock which can effect your point of impact compared to the standard nock. I have used them a bunch. They are excellent for seeing your point of impact on an animal and for finding your arrow. They also show up on video very well. The only thing is that they do not always work. (from my experience) and if you practice with them all year long, the battery will go dead. I like the easton Tracer nock better because you can turn it off and on, and not waste the battery.
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