No. Not cut it down at all. It did have a white plastic cover, but that broke. The thread on it is the regular British broom thread, so it doesn't fit perfectly on the adapter, but it hasn't come off yet. I think that a self-tapper might be a good idea to hold it on a bit more securely.
As you can see, the bristles are about 5 inches long. What you can't see is that they are very densely packed. There's quite a lot of scrubbing power in there.
(I can also use it on conservatory ridge cappings. Then I use it with a sort of stabbing motion to get into all the tiniest nooks and crannies and it really shifts the algae and muck.)
It wasn't cheap. It was about £16 from B&Q many years ago.
It has earned its place in my toolkit.