Rex Salazar's power suit is a specialized suit that's initial purpose is to give Rex better range when flying on his Sky Slyder. The suit is entirely technological, considering that he is able to make it disappear when communicating with it.
The suit first appeared when Rex was flying to Abysus with Circe. He mentioned to her that Holiday was correct about the suit giving him more range when flying.
Again, he wore it when in Hong Kong. In order to take the suit off, he used his technopathy to communicate with it and change back into his normal attire; which was underneath his power suit.
It was unknown whether Holiday invented the suit herself.