The CP20xx are external lithium ion battery packs compatible for DELL laptop computers. There are three models: CP2022 (20V, 2200mAHs, 44WHs, 128×71×24mm,288kg), CP2045 (20V, 4500mAHs, 88WHs, 116×71×39mm,364kg), CP2036 (20V, 3600mAHs, 72WHs, 427kg), all applicable for DELL laptops which require an input voltage (laptop?s adapter output voltage) between 18-23V, adjusting automatically by embedded intelligence device. They are the most exquisite external battery packs in the world.