The Clarity ones are a set of four, and the normal retail is £19.99, although right now, the Black Friday weekend, they are a third off, which is a great time to get them if you want to stock up.
The other set are Decorators Sash Brushes, from the Toolstation, and are £6.99 for a set of three, which is a great price point, assuming they do the job well. I looked at these as I'd seen someone somewhere on FB say that B&Q Sash brushes were a good alternative, and again, much cheaper. I did a Google search for the B&Q ones, as our B&Q has recently downsized a lot, and didn't want a wasted journey. Anyway, the ones that came up first in my search were a set by Toolstation, and the pic shown made them look visually at least as being very similar.
As you see, the Toolstation set does not have an equivalent to the largest Clarity brush . The Code for them is 78094.
They do appear very similar in looks, and as for the feel, I would say the Clarity ones are slightly softer, but only very slightly. Maybe slightly less rigid than the Sash brushes, but it's not a big difference.
To test them out, I used two types of Clarity card, their 7" square Stencil card, and some A5 sized Theuva card, which has a slightly glossy coating.
I used 3 Distress Oxide colours for testing, and worked on a blending mat.
This is the result from the Toolstation brushes. In the video you will see the comparison colour by colour, I just forget to take individual photos! Theuva card at the top, Stencil card on the bottom.
This is the pair using the Clarity brushes. Again, Theuva card on top, Stencil card on the bottom.
I then did a small comparison of the Toolstation brushes with an Inkylicios Blending brush.