Product review (5 stars): APRILAIRE GENUINE PART
You don't have to be an expert DIYr to replace this - it's really easy - and an HVAC guy will charge you about $80 for the visit and $25 for the pad - do it all yourself for $12! If you have hard water you may have to remove this once or twice in a winter season and soak it in water/vinegar to shake off the deposits.  Otherwise it will definitely last a full winter season.