Velcro SLS (Space Launch System) is a quick and dirty treatment of the USAF's proposed modular space launch system. The smallest version lost out against the Titan III. The larger versions would have launched LUNEX, the USAF lunar missions....
You MUST INSTALL the Velcro Rockets add-on (http://www.orbithangar.com/searchid.php?ID=3388) for this add-on to work.