These pics are Nylon, but it is different class of Nylon, compared to Dunlop Standard Nylons, being stiffer and having more attack and Loudness, in The Sound. A similar sound, feel and attack to The Herco Extra Light Nylon.
But the different edges and corners make a big difference. The main feature, the serrated edge, produces a 12 String kind of sound, which is more Treble than the Harley Benton Fantails, which have The Celluloid Sound.