The VerticalMouse 4 Mac Bluetooth is the next in Evoluent's series of ergonomic mice. An ordinary horizontal mouse requires your forearm to twist away from its natural position, but not the VerticalMouse! The grip is the same as an ordinary mouse, just turned sideways into a handshake position which avoids forearm twisting for comfort and good health. Many users, including medical doctors, ergonomists and physical therapists, have said the Evoluent VerticalMouse provides superior comfort and even relieved their wrist pain. Please note: only suitable for Mac systems only, not compatible with Windows systems