Well it's not Gardiner's creation for a start, its made by a company called Marolex.
A decent consumer product maybe, but I highly doubt it would last long in use as a window cleaning trolley.
And how do you fill it?
It's missing the most obvious benefit of the pure freedom trolley, which is interchangeable barrels.
The idea that when one barrel is full you just swap it out for a new one out the boot, is why the pure freedom trolley is so popular. This one is going to need filling somehow. From a tank in the van perhaps? But if you have a tank in the van why would you want a trolley? Silly.
Just buying in someone else's plastic trolley that's probably not up to the job and that only holds 20 litres and then whacking a great fat markup on it is, in my opinion, LAME.