Depends what i'm playing, if i'm using an acoustic guitar i normally go with 0.73 nylon plectrum but if i'm playing electric guitar i use 0.73 tortex plectrum. Even though they are the same thickness the tortex has a lot less flex than the nylon, i've experimented with lots of different ones over the years but have settled on these and they've been my go to plectrums for a long time now.