Made by Waterway
Hot Tub Filter Mounting with Grate
Part Number 400-9030
Plumbs into 2" plumbing (The rear is a socket so it fits 2" pipe) and fits an 1.5" MPT course threaded filter, like the PWW50 filter made by Darlly.
Fits 7cm hole and has a 5cm thread.
This is a useful item if your building your own hot tub and want to use paper filters, also great for repairs. The grate built in stops medium sized objects going into the plumbing if the paper filter has a fault or isn't fitted.
Comes complete with nut and seal, however you may want to seal it with silicon instead of the seal.