A Dmoney says Sozo are a "premium" brand capacitor.
I class "premium" brand components as those manufacturers make a song and dance about in their promotional literature, usually with the acknowledgement that these components are more expensive than the standard components used by rival manufacturers.
And if you think guitar amp manufacturers are bad for this, have a look at some of the valve hi-fi manufacturers!
Sozo do several types of capacitor, however their most popular one is a "reproduction" of the Mullard "mustard" caps found in virtually all the classic British amps up to the mid 70s (eg Marshall, Hiwatt).
The key feature of these caps is that they have a polyester insulator and they have an identical aspect ratio to the old Mullard mustard caps.
Modern caps tend to be shorter and fatter so that there more tabs on the ends to connect to the leads. This reduce series inductance and this increases high frequency response.
I can't comment of the sonic properties of Sozo caps as I've not had any experience of them, and am unlikely to in the near future as they are not RoHS compliant, so can't be used in new amps sold in the EU.
Obviously there is plenty of snake oil out there; what does worry me about the Sozo caps is the page on their website that explains why their caps need "breaking in".
Regardless, in the scale of the whole purchase I don't think $20 is going to break the bank, so I don't have a particularly strong opinion on this.