Celestron Telescopes 2.5 amp 110v AC Adapter 18778 is a plug-in power source for many of Celestron Telescopes. Celestron 2.5amp AC Adapter 18778 replaces Celestron AC Adapters 18772 and 18773 . Celestron AC Adapter 110V 18778 is compatible with all Celestron Nexstar i, Celestron Nexstar GPS Telescopes (also compatible with Celestar 8, Ultima 2000, CI700, CG Telescopes). Because Celestron AC Adapter 18778 has a 2.5 amp (not 1.5 amps like older models) 12-volt DC output, it is compatible with larger Celestron Telescope which require 2 amps (some models of Celestron Advanced Series Computerized Telescopes, Celestron CGE Telescopes, Celestron CPC Telescopes). And of course this Celestron AC 110 V Adapter is suitable for all Celestron Computerized Telescopes, which require 1.5 amp, and allows a telescope to be connected to ordinary power outlet.