Dear Sirs, Array Electronic is a legal exclusive of manufacturing TELECRANE series product since 1998, the model include F21-E1B, F21-E1 etc. , marketing covered over 80% share in China . Over 200,000sets annual had been sold over 11 years. Array become a leading brand in Crane Radio Control. UNIQUIE ADVANTAGE SYSTEM FEATURES - F21-E2B series: * AUTO FREQUENCY SELECTION--- No channel Changing required when multiple radio Controller at the same time. * PROGRAMMABLE SOFTWARE ---- great flexibility to meet most of the applications, allows many settings such operation function , emission power etc. * INTERIOR E-CARD ---System data carried easy transfer to a spare Transmitter & Receiver to resume work without any downtime. SAMPLE SHIPPED within 7 Days To prove how excellent of our system quality system features, sample order are welcome, Credit Card, (visa , Master) , payment on line (paypal) acceptable .