Disktivity is the LED that's missing from your Mac. Disktivity provides you with an unobtrusive activity monitor that displays the current status of your hard drive. Features include: - 4 LED's (Idle,Read,Write,Read/Write) - Option to Launch At Login - Option to display text next to the LED indicating status - A Legend that shows you what each color represents A simple no fuss solution to an everyday problem. No more guessing if your hard drive is busy.