These are pretty standard picks. I think that they are most suitable for playing something smooth on a bass guitar, because:
-they don't have a great grip (a bit slippery), so it's safer to play something slow with these. -they are also not very durable and are quite thin, so playing something chilling may compensate that. -standard shape is more suitable for playing bass (that's a personal thing, though).
So the bottom line is: pretty average picks, but if used for very specific kind of playing, they hold strong, given the low price tag. I would recommend to buy these for the purposes close to what I described.
This is a very good set of pics, for a very nice price. They are suitable for stromming and for picking. One minus is that on hard stromming on acoustic it leaves this white gel-dust. Also this scratches the pick-guard area when playing you hit it.