HT NSL-1 Nightstar Tip-Up Light with Dual Light System. This product is a durable and designed for ice fishing applications. Provided by HT. Take out the plastic strip between the batteries before use. Flip the switch on to one side or the other, then set the tip ups flag wire under the trip bar and the light is ?OFF?. Once the flag wire goes up when a fish strikes, then the light will go on and flash signaling that a fish is on.