To replace the bulb, simply switch out the original one, refer to the instructional video for guidance limited to 3-7 C/D-Cell Maglite flashlights. The energy efficiency will offset the expense through reduced battery usage.
Replacing it, is as easy as changing the original bulb, please you may also see the Video how to proceed ONLY to be used for for 3-7 C / D-Cell Maglite flashlights The energy efficacy will compensate the cost by using fewer Batteries