Features Safe:Ultrasound dosage is under the safe standard 50% of National standard. Durable:Huge capacity battery,work more than 12 hours after full charge. Convenience:The structure design of the equipment accords with human engineering.Single key to control the operation of all functions. Setting the main unit on the base is not only for automatic charge,but also for overvoltage protection function. Sensitivity:Monitor 9 weeks fetuss blood wall pulsate with the high sensibility probe. Probe:According to different weekly diagram of pregnant,2.2MHz or 3.3MHz can be selected. Speaker:Quality "Sanyo" speaker take more clearly and loudly.