Surface for the 4PL (Also suits 2PL / 3PL) Specification 2.4GHz FHSSDimensions 39x26x10mm Weight 8.0g Frequency 2.4GHz Use Surface Channel 4CH operating voltage 4.8 - 7.4V This receiver does not work with the Futaba FASST system. Use only with Futaba 2.4GHz FHSS system. Futaba FASST systems and FHSS systems are not compatible with each other.