These probes/sensors work with the FD300 and FD320 Fetal Dopplers. We have 2Mhz probes, 3Mhz probes, and 8Mhz vascular probes. The 2Mhz/3Mhz probes can be used to hear your baby's heart beat. The 8Mhz probes are vascular probes. If you want to hear your baby's sound/movement, please choose the 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 are designed for vascular monitoring and provide detection of vein blood flow and arteries. The 8MHz vascular probe provides the highest resolution and widest detection range out of all three probes. It is intended for examining surface vessels.