This is a Kero Ball ケロボール.
It is a multi-function Keronian weapon. This handy ball is capable for Realization, Electrocution, Teleporting, Cloning and other stuff like Levitation. As powerful as it sound, this Kero ball is merely a casing for something more wonderful.
Opening up, you will get to see the goodies inside. None other than Keroro himself.
Being a Gunpla fan, Keroro was seen being busy making his Gundam model.
This series have some other model available. I don't know why the same series had two Giroro design...
Looking at Keroro busy working away with his gundam model, it remind me of some SD Sangokuden Gundam I have yet to fix it.
So do I keroro san. :(