Mix of famous designs of brettbb (http://www.rcgroups.com/forums/showpost.php?p=23772243&postcount=1) and Impact RC (http://www.rcgroups.com/forums/showpost.php?p=32561744&postcount=383) from rcgroups.comChanges from those designs:Rail changed from square rail to angled with the purpose of having lighter and more compact rail.