Sonoline B Plus Water Resistant Baby Activity & Heartbeat Monitor – Red (Plastic). The Sonoline B Water Resistant Baby Heartbeat Monitor from Baby Doppler with 3MHz Probe employs the latest technology in Baby Heart Monitoring. This amazing device allows any soon to be mommy to monitor/hear the baby’s heartbeat with ease and reduced static. The back-lit LCD Screen displays the baby’s heartbeat (FHR), and an audible sound is heard in real-time from the built-in high-quality speaker. It has three built-in modes that allow the user to view the heart rate in different display modes. This heartbeat monitor is suitable for use after the 12th week of pregnancy. It gives you peace of mind and reassurance throughout the rest of the 28 weeks! This unit is equipped with an audio output for headphones or sound recorders (headphones or recorder NOT included) and a built-in loudspeaker. The Sonoline B Handheld Pocket Heartbeat Monitor also includes a water-resistant 3-MHz Doppler probe. Sonoline B handheld Heartbeat Monitor is the best quality equipment used by expectant mothers to monitor and hear the baby’s heartbeat whenever they want, even when they are out and about! The heart rate can be seen on the clear backlit LCD screen and the sound can be heard via the built in speaker. It is battery operated so it is fully portable and amazingly lightweight – with only 2xAA batteries required it can continuously run on for at least 10 hours.