Fetus Ultrasound Doppler

Hi, does anyone know where to get a fetus ultrasound doppler? (To listen baby’s heartbeat home device) Wanted to get one so time to time I can listen to baby heartbeat whenever I’m worried and dont need to keep going to clinic ultrasound 😬 I know lazada and shopee are selling but I wanted to get it from the store/mall. Im a little worry the ones selling online might not be safe for baby if it’s not an authentic device.