NightWriter Battery and Ink Refill Kit - Fits NightWriter LED Pen. AG4 battery pack and ink cartridges This battery and ink refill kit fits the Pilot's Pen "NightWriter", unique LED Powered Pen Includes five (5) ink refills (Black ink) and 4 complete battery pack refills - including housing. Easy to replace by unscrewing the pen top removing the old battery pack/ink and replacing with the new pack Economical replacement battery pack extend the usefullness of your Pen See our video showing ink/battery replacement: https://www.pilotlights.net/night-writer-led-pen-2-pack