This is used to hold the float switches from Bulk Reef Supply on the edge of a bucket so that your RO/DI unit will automatically turn off when the bucket fills. I highly recommend using the adjustable float switch due to the angle that the float switch is mounted at (to allow for clearance for the product line from the RO/DI unit).

Here is the float switch: https://www.bulkreefsupply.com/adjustable-ro-float-valve.html

It is designed specifically to snap over the edge of the Homer buckets from Home Depot, but it might work on other 5 gallon buckets as well.