This Trackball Mouse from Kensington is ideal for people with limited hand function. The ball is large and easy to use, even for people using typing sticks and other devices to press keys on the mouse and keyboard. The mouse has four programable keys that are easy to set. The best feature, from my personal experience, is being able to set one of the keys for click, lock and drag. The key allows people to use a single hand to click and highlight a word, sentence, or paragraph to copy or cut and paste.