These waterproof interchangeable probes work with all Edan Sonotrax fetal dopplers, we have 2Mhz probe, 3Mhz probe, 4Mhz vascular probe,8Mhz vascular probe. The 2Mhz/3Mhz probe could be used to hear your baby's heart beat. The 4Mhz/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 4 MHz and 8 MHz waterproof probes are designed for the Vascular monitoring and provide blood flow in veins and arteries detection. There probes provide 4.0 and 8.0 MHz frequency correspondingly. The 4 MHz as a vascular probe with the lowest frequency features the deepest penetration level and best suits for examining blood vessels. The 8 MHz vascular probe provides the highest resolution and wider detecting range out of three. It is intended for examining surface vessels.