The Federation series consists mainly of extremely expensive, intergalactic-themed LimitedU crown & tiara hats with names that are mainly based on royal and noble ranks.
There are currently seven Federation crowns on Roblox (one of which is offsale), as well as four Federation tiaras and many other Federation-themed accessories.
Royal Crowns of the Federation
Note: Crowns and tiaras are ordered based on the hierarchy of their titles as well as whether they are part of the main series or modified versions of existing items.
Royal Tiaras of the Federation
Ceremonial Shoulder Guards