Leaving aside the question of what a "jet rocket" even is, this seems to be the same company that sold the Polaris Nuclear Submarine. That ad was from 1967, so this may be a similar vintage.
Recently, a 1964 Jet Rocket Space Ship by Honor House was offered on ebay for $1500. Like its tank and submarine counterparts, the rocket is made up of cardboard pieces.
https://secretfunspot.blogspot.com/2012/01/1964-jet-rocket-space-ship.html