Summer infant clarity prenatal listening system allows you to hear your babys heartbeat the two sets of microphones included in the summer prenatal system allows you to hear the babys movements and heart from approximately 28 weeks its easy to use as it simply straps onto mums tummy and is not invasive it comes complete with an auxiliary lead which can be connected to your computer it is also completely safe and non invasive with no ac current ultrasounds or radio waves used summer in