This plate is clamped onto the end of your sparge recirculation loop, to gently deflect the water into the mash kettle. It is intended to be placed underneath the surface of the liquid.
If you want to use the whirlpool arm as a sparge arm when mounting it in the kettle handle tri-clamp mount, this is the additional piece you will need to make it work.
See the linked product description for more details. The clamping range is 18-22 mm, so you can clamp it directly to our reinforced silicone tubing.