Hook: Floor Small (Green Square)The Illuminated Pylon decoration fits into a small green square floor hook.
Hook: Floor Medium Narrow (Blue Rectangle)The Illuminated Pylon decoration fits into a narrow blue medium rectangle floor hook.
Hook: Floor Medium (Blue Square)The Illuminated Pylon decoration fits into a blue medium square floor hook.
How to Get an Illuminated Pylon Decoration
Cartel Pack Decorations
The Illuminated Pylon decoration can be dropped from Ultimate Cartel Packs, which were released on the Cartel Market and bought with Cartel Coins. Cartel Packs, including the Ultimate Cartel Pack, include a random selection of items from the Ultimate Cartel collection of items. You aren't guaranteed to get an Illuminated Pylon decoration from a Ultimate Cartel Pack, but it is one of the few ways to get an Illuminated Pylon deco apart from buying it on the GTN from another player.
If you're looking to get a Illuminated Pylon, 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. If it's very rare and not available on the Cartel Market, you could try buying from the GTN and hope you get it.