Hook: Floor Small (Green Square)The Underworld Starship Chair decoration fits into a small green square floor hook.
Hook: Floor Medium Narrow (Blue Rectangle)The Underworld Starship Chair decoration fits into a narrow blue medium rectangle floor hook.
How to Get an Underworld Starship Chair Decoration
Cartel Market Decorations
The Underworld Starship Chair deco is part of the Underworld Essentials Bundle, a set of decorations that you can buy directly from the Cartel Market with Cartel Coins. All decorations from the cartel market, including the Underworld Starship Chair deco, can usually be found on the Galactic Trade Network (GTN) and bought from other players with credits.
If you're looking to get an Underworld Starship Chair, the easiest way to get it is to head to the Galactic Trade Network (GTN) in SWTOR and buy it with credits from another player. You can also buy the full Underworld Essentials Bundle from the cartel market or GTN, which includes this deco and a few others that match.