Fishing bite alarms can make it much easier to know when you have caught a fish. They are particularly useful when fishing in the dark or when you have more than one rod to keep an eye on. These come in a set of three in a box. They are rubber finished and the case is made from EVA. They have a blue LED light on them with a high output speaker. There is an on/off button and it is possible to control the tone, volume and sensitivity. There is a 2.5mm jack for an illuminated swinger as well. Each needs a 9v battery which is not included.