With arm and shoulder pain I went to the orthopedist, in which intense conversation with the doctor, it was also about the issue of how long you sit at the PC ... etc. Neither does indeed something wrong .... but where these complaints come because actually ???? After this conversation with the doctor I ordered a "Orthopedic mouse". That's now a few weeks ago - I never thought that may arise from a "mouse" this pain. For me there will never be again a "simple mouse". The pain is like away. Dehalb for this "orthopedic mouse" from me 5 stars !!!