Replacement logic board for LiftMaster ATS211X operators, part number 41A5021-1HATS. It's the one with the red smart/learn button. If your opener's acting weird with remotes not responding, intermittent operation, or the board just died, this is probably the part you need. The logic board is basically the brain of the operator, so when it goes out nothing works right. Make sure you've got an ATS211X series unit before ordering because logic boards are model-specific. A board from a different series won't work even if it looks similar. Check your existing board's part number to confirm.