This was a one-of-a-kind Star Destroyer that only transported Elite Commandos at the end of the Clone Wars. The design was meant to mimmick the look of Imperial Star Destroyers, so the commandos (who were against Palpatine)could travel the galaxy without alarming the Empire.
About this creation
Some mini ships included in this moc
More mini ships
Holotable displaying a battle with two observing jedi
Mace Windu talking via hologram to Supreme Chancellor Palpatine