Replacement keypad for the legacy Respironics REMstar Plus with C-Flex, Pro, and Auto CPAP machines. This is the five button keypad. The buttons are: heat, ramp, start/stop, left arrow, right arrow. If your CPAP machine doesn't turn on immediately when you press the Start/Stop button, or if you have to press the buttons repeatedly and firmly in order to get them to work, then you likely need a new keypad. CPAP-Supply.com has written an article showing you how to replace your keypad. Check it out here!