The choice of picks is (also) a personal matter - like the guitar and the strings :D
In my opinion these picks works best on Western guitar, gauges '12 and above. For me, this 0.6 pick, delivers precise and clear tones, which I particular values in strumming on acoustic Western Guitar.
A minimal less 'round/mellow' sound than that of picks made of celluloid - of the samme thickness.
The surface appears/is smooth, but so far I've had no issues concerning slipping.