This 3Mhz probe/Sensor works with Sonoline B, FD-200 Fetal Doppler.

These interchangeable probes work with sonoline B, FD200 fetal dopplers, we have 2Mhz probe, 3Mhz probe, 8Mhz vascular probe. The 2Mhz/3Mhz probe could be used to hear your baby's heart beat. The 8Mhz probe are vascular Probe. If you want to hear your baby's sound/movement, please choose 2Mhz/3Mhz probe.

A 3MHz probe is recommended to detect a heart rate in early pregnancy (8-10 weeks gestation). A 3 MHz has also been proven to work well throughout the pregnancy.

A 2MHz probe is recommended for pregnant women who are overweight.

The 8MHz probes is designed for the Vascular monitoring and provide blood flow in veins and arteries detection. The 8MHz vascular probe provides the highest resolution and wider detecting range out of three. It is intended for examining surface vessels.