A-100s is a time fetal doppler, which is designed for clinic and small hospital. It is a lightweight and space-saving time fetal doppler, which can be operated at bedside and acted as handset. It is designed for use in the antepartum applications. Feature: Indicates fhr as numeral and outputs fetal heart sound. Patented acoustic design enhanced vivid sound. High sensitive 2.5 mhz doppler probe. Rtc timer inside can display day/hour/minute. Built-in rechargeable battery for 24 hours continuous work Medical-use switch power supply guarantee 50, 000hrs working life.