Features Safe: Ultrasound dosage is under 50% of the standard. Durable: Huge capacity battery, work more than 12 hours after full charge. Convenience: Single key control. Automatic battery recharge and protection. Sensitivity: FHR of fetus 9 weeks up. Probe: According to difference of pregnant week, users can 2.2MHz or 3.3MHz probe. Specification Probe: Solid and durable, anti-shock and anti-falling down. Ultrasound frequency:3.3MHz or 2.2MHz +3% Ultrasound intensity: <2.5mW/cm2 Display: LED, display real-time FHR. Power: AC 220V 50Hz, DC18V. Rechargeable battery: 1100mAh(can work more than 12 hours continuously) Size: 240mm*160mm*115mm Weight: Main body 1.12kg, charger 0.64 kg Standard: ISO9001: 2000 Reward: It has won many big bid authority organization like MOH, UNFA etc.