All DigiDop fetal probes provide the sensitivity and reliability you need. All probes will work on all DigiDops for maximum versatility. Our 2 and 3 MHz fetal probes utilize our exclusive eXtended Depth – XD™ technology that has increased sensitivity at closer depths without sacrificing it at deeper depths. These probes create more than six times as much signal at some depths that other probes. All our OB probes have a smooth contour design that is comfortable to hold, comfortable for the patient, and easy to clean.