Robotis RX is a little taller and little slower that the Sony Qrio. RX measures in at 60 cm and can run at 500 meters an hour (about 0.3 mph). This is quite an accomplishment for Robotis. Still, they are going to have to go just a bit faster to beat Qrio's Guiness world record speed of 828 meters an hour (0.5 mph). Run, Robotis, run!