The slotless BLDC motor DS16 from Nanotec has a stator made of ring-shaped metal sheets with a flat winding on the inside. As the windings do not have an iron core, the motor's inductance is very low and the current increases quickly. According to the manufacturer, iron losses are also greatly reduced and the motors are more efficient. In low-speed operation, the lack of torque ripple has a positive effect. As the magnetic field is not amplified at the pole shoes as with standard BLDC motors, there is no cogging torque. The DS16 is available in three lengths: In size S with a length of 28 mm and an output of 3.7 watts at a maximum of 27,000 rpm, in size M with a length of 40 mm and an output of 10 W at a maximum of 30,000 rpm and in size L with a length of 56 mm and an output of 25 W at a maximum of 29,000 rpm. The low inductance of the slotless motors in combination with the PWM frequency of the controller can lead to a high current ripple, which causes additional heating. Additional motor chokes must therefore be used between the controller and motor.