According to dcuowiki, it is from legend of Krypton 3 briefing, but I don't see the entrances to the star lab research facility where the blue exclamation marks are located. http://dcuniverseonline.wikia.com/wiki/LexCorp_(Style)
it comes from inside the old star labs facility lab building and the new lab building i believe possibly as a mentoree of either luthor or super man don't remember which if either you have to have but i believe it's part of the super man/lex mentor starting missions. sort of like how only wonder woman/circe mentorees can get the minotaur shoulders. the developers occasionally change rewards without updating certain external pages, so that might explain why.
here's some mentor mission specific items and styles: dualwield claymores (the third clue) batman, minotaur shoulders (chinatown electronics) wonder woman, lex corp chest (super man). similarly the android styles (android batman/joker heads) only drop for players who chose those mentors and cyborg's hand blaster style drops for villains running through the trigon rising arc in forum of the 12 caesars.
There is a difference between drops, briefings/investigations, and mission rewards (from the journal). Drops and briefings/investigations can be received by anyone, they just require you to be in a group with someone that has the correct mentor. Mission rewards can only ever be completed by someone with the appropriate mentor. Also, several of the mentor specific instances are now challenges. I know the last two locations for each mentor are not challenges yet, and I believe one of the two level 15 instances for each mentor aren't challenges either.
briefing, it's a master briefing/collection where you have to complete two or more whole briefings or collections.
