Hans Grohe iBox Universal Plus Rough 01850181 Installation Instructions / Warranty page 39

Installation
Make sure that the black self-sealing filter gasket (already
installed) is screwed firmly into the ball joint.
If desired, place the boot on the shower arm, and push
up out of the way.
Carefully install the showerhead on the shower arm.
Use a 19 mm wrench to tighten. Be careful not to over
tighten.
Pull the boot down over the connection.
If the flow of water becomes less over time, remove and
clean the filter gasket.
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