Castle Creations Quadpack 35Amp Multi-Rotor Pack Electronic Speed Control (4) Castle multi-rotor ESCs come programmed with default settings optimized for multi-rotors using direct drive out runner motors. Castle multi-rotor ESCs contain operational tones and Error codes when certain conditions are present, allowing the ability to diagnose and resolve common problems with ease. Quad pack 35 ESC accept input voltages from 2S LiPo to 6S LiPo Bec voltage is 5.5 Volts with a 7 amp peak output and this package contains one multi-rotor 35 with a beck and three with no beck Esc Dimensions are (Width) 22.4mm, (length) 49mm and (depth) 8.4mm and weight (W/wires) is 27.8G.