Belgique Rocket-flown on SEPT 4, 1935; postmarked DUINBERGEN. "RV 3" rocket used by Karl Roberti, rocket experimenter. Blue NRB label; red RV3 cachet; two-line stamped cachet on reverse. Cover was numbered 59 and signed by Roberti in green ink. EZ 5C1b - no rocket stamp; no "Control Cachet