This is a very thin string. I’ve never seen squash strings listed as 20 gauge before. The Tecnifibre 305 comes in a 1.1mm string that’s listed 18 gauge. I’m not sure how to measure that myself — might need to invest in a micrometer or something.
Here’s a video review I did of this string:
Head Reflex 1.2mm (18 gauge)
This one’s listed as 18 gauge / 1.2 millimeters: