These reflux dividers are to be used with a electro-magnet and a timer. These have a swinging funnel mechanism which is operated magnetically from outside to remove the condensate or to return the reflux.
Through this correct control or reflux-ratio is possible. Funnel remains at 100% reflux position when magnet is inactive.

DN2 is used for insertion of a thermometer pocket. A liquids is recommended on the distillate outlet of this reflux divider to prevent the vapour passing directly to the receiver