Focusing Element IV is a research and development part used with high quality plans to create powerful equipment mods.
Obtained from
The item is a possible reward for defeating bosses in instances such as tier 4 hard alerts, tier 4 raids and tier 4 [operations]].
Trivia
While non-legendary players can get this item, they can only use it in crafting mods if a legendary member provides other required items that cost over 2000 (for ex. Equipment Interface Type IV)