The ReefLED 90 Universal Mounting Arm is perfect for aquariums that need a tank mounted bracket to support their light. Red Sea's Mounting Arm attaches securely to the back wall of your aquarium and can quickly be lifted to an upright position for easy access to the top of your aquarium for feeding or maintenance. The support will perfectly position the light on aquariums that are 18.25" - 27.5" front to back. Assembly is quick and can be completely removed and reinstalled from the aquarium in a matter of minutes.