Water level indicators are an ideal way of viewing the water level of your tank at a glance. The way Apex water level indicators work is it has two floats attached to a rod that can slide freely up and down, indicating the level of the water in the tank. This indicator can be easily adjusted using the patented uni-ball joint and can adjust to any water tank roof angle. This product is suitable for all water tanks and is manufactured from UV resistant premium quality materials. Spare extension tubes and floats are both available.