Makerfire 4pcs ESC 20A BLHeli Brushless Speed Controller for QAV250 Racing Drone Based on BLHeli firmware with low voltage protection, over heat protection and self check functions. Works with 2S to 4S input - Rated at 18A continuous and 30A burst Perfect for MT1806 MT2204 brushless motor in QAV250 and other mini Quad. Support OneShot ultra-high speed control and Bi-directional rotating. All N-FET design with external oscillator for steady performance across different thermal and voltage conditions.