LG Side By Side Refrigerator X24ff knock knockDISCRIPTION.. x24ff knock knock" is likely a reference to a specific model of the LG InstaView refrigerator,, which has a "knock knock" feature that illuminates the inside of the door when you tap the glass twice. This allows you to see inside without opening the door, which helps keep cold air LG Instaview technology .. The "knock knock" feature is part of LG's InstaView Door in Door refrigerator system How it works.. Knock twice on the glass panel