The Black Box is a magical and technological talisman that can combine the symbol powers of all the Samurai Rangers. It was created by the first Red Samurai Ranger but was unable to complete it. The rangers recognize how much using the Black Box could drain them but eventually decide to retrieve it from Daisuke at The Tengen Gate. Daisuke claims that it was the most powerful Samurai weapon ever conceived and that few even know of its existence. Ji, recognizing Antonio's symbol power and symbol hacking skills, asks him to complete it using his Samurai Morpher to channel the other rangers' symbol power into it.
Antonio then merged all of the existing Samurai powers at the time into the box. With it, one Samurai Ranger can take on all the powers and access Super Mode. The Black Box then attaches to the Spin Sword magnifying its power.
With Super Mode activated, once the rangers call on their zords, the ranger with the Super Mode accesses Super Mega Mode while the rest access Mega Mode. The Black Box then attaches onto the hinge of the Super Mode ranger's Mega Blade while in controller mode. When the need arises to use the sword mode in cockpit, the Black Box is moved to the offset section of the Mega Blade's hilt.
More Info: http://powerrangers.wikia.com/wiki/Black_Box