Model A8200S1Fetal Doppler is a low- cost and high performance fetal heart beat detector. It is applicable for the private obstetrician's office, antepartum clinic, obstetrical department of hospital and remote monitoring situations, or using in home. It has an audio output port connected with earphone or recorder with audio input. It uses 9V battery standby for 3 months or continual used for 5 hours. FEATURES Lightweight and portable, Easy-to-use Long life design, dust proof Built in Hi-Fi speaker, clear fetal heart beat sound High sensitivity interchangeable probe Audio output port Optional rechargeable battery and charger.