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