This is a Colorado Time Systems External Horn that is designed to be used with the Otter scoreboards like MS-0140 for Water Polo. You may want or need an external horn if you want sound coming from the scoreboard rather than the deck clocks.
The external speakers have 8 selectable, distinct tones. They have separate audible tones for shot and period horns. The horn sounds automatically when period/shot clock counts down to zero. The horn can also sound manually as directed by the operator.