This depth marker is a 5" black number on a 6x6 white tile and represents the depth of the pool. A smooth tile is used inside the pool and an abrasive tile is used on the deck.
The most common use for a depth marker is to show where the shallow and deep areas are in the pool. Depth markers are always used in commercial pools, but can also be used in a residential pool. They are a great safety tool for any pool.
The size and style you need will depend on what city and state you are installing them in. Check first before ordering to ensure you are ordering the correct size and style for your pool.