Kits are for installing removable air channels on non-current models produced without them.
Kit p/n 2500062 - for E-Classic 2400 models produced without removable side air channels.
Kit p/n 2500030 - for E-Classic 2300 models with serial number prior to E17328 (standard models) and prior to E17455 (dual fuel models). These models can be identified as having a brick ledge in the firebox. Kit p/n 2500136 - for E-Classic 2300 models with serial number E17328 and higher (standard models) and E17455 and higher (dual fuel models). These models can be identified as having a flat side in the firebox.
Kit p/n 2500006 - Rear Air Channel Plate for all E-Classic 2300 models.