Very Handy, we've purchased a few of these over the years, just ensure there is a good seal "bodged" into place AFTER all cables are through to prevent air leaks (draughts between brick / blockwork) & the possibility of rodent ingression (you never know)! ..we sealed the gap with flexible silicone so that it could be removed at a push, ..well actually a sharp tug.
If you are wall mounting these are indispensible helping keep kit neat & out of sticky hands ((kids))as well as reducing wiring clutter
We also used a black stiff backed felt to create a more even, black & effective seal.
You will still need a wire coat-hanger to "fish" for your cable through the wall (setting this up) but that only takes a matter of minutes, whereas the effect will be hidden for years, IF you buy good quality cables.
Lastly remember, you MIGHT need a pair of these not necessarily a single "cables in, cables out".