SG type electromagnet: the magnetic field has a fixed air gap, the double yoke structure magnetic circuit is closed, and the magnetic field direction is horizontal; it has excellent rigidity and stability, and is suitable for experimental research that requires high magnetic field uniformity and stability. Used for Hall effect research, magnetoresistance effect research, hysteresis extension research, torque magnetometer, force magnetometer, magnetic susceptibility measuring device, magnetic material measuring device, etc., especially suitable for vibrating sample magnetometer, nuclear magnetic resonance Application of high-precision instruments such as magnetometers. The pole head can be replaced to change the magnetic field air gap.