These are pretty good, actually! I have been given a load of exercises by my physiotherapist for shoulder problems and these things serve my exercise regime well. In particular I can adjust the weights appropriate to what particular bizarre act she's given me to do, from 1¼ kg ro lifting myright arm forwards to 2 x 6kg for lifting both arms up while bending at a 45 degree angle.
It's just a shame that none of these exercises seem to be improving my condition, but I guess it's my own fault for being sixty five years old!