Photon Probe (Classic) Skl Lvl 2 D-ES3026 Many years ago, Estes had & still has some of the best rocket designers in the world! With that thought in mind, it was decided to go to the archives & reintroduce some of those famous kits that rocketeers of all ages loved. The Photon Probe is one of the first in the " Classic Series" to be re-released. Flying on standard engines, the Photon Probe is a must have for all serious rocketeteers!