Modelcraft gy403 heading hold gyro modelcraft gy403 this gyro unit is a compact stabilising system that detects positional changes using a mems sensor the subsequent output being used to control servos to counter positional errors the unit operated in one of two modes normal mode when output is dependent on gyro vehicle integration heading hold mode output is dependent on gyro position only br br the gyro is suitable for use with either analogue or digital servos and is switch