Punto Blanco is a major Spanish maker of underwear for men and women, and they happen to carry a few thongs for men that are readily available on Amazon in Europe. I ordered a box that came with two pairs, called the "Invisible 2 pack string" in black and grey, which were the cheaper ones of the bunch.
Punto Blanco Invisible 2 pack string
I got these thongs at £17 for a box of 2, which I thought is a lot cheaper compared to other major thong manufacturers like HOM, Diesel, Armani, or Calvin Klein. They are made of cotton, and I'm not sure what made them 'invisible', since they still had a protruding elastic lining. I thought the cut looks appealing from the back, although from the front, it looks like any run-of-the-mill briefs you'd find from other manufacturers. As such, the front section fits the package rather snugly, although I find it a bit tight at times. Since it looked very ordinary apart from the thong back, I thought that these would be suitable to wear in professional instances like on the job, at school, or during formal events.
Fit: 4/5
Look: 3.5/5
Comfort: 3.5/5
Quality: 4/5