This item belongs under health and beauty, but due to it's nature must be categorized here. This unit is popular amongst pelvic floor physical therapists for the treatment of pelvic floor dysfunction to include urinary incontinence, fecal incontinence and overactive bladder.  I owned a clinic and no longer need to own multiple of these devices.  This is the part of the unit you hold in your hand, NOT the part that goes internal, thus it's OK to sell pre-owned. There is a number written in Sharpee on the case of the device and also on the back of the device that do not match.  There is no accompanying instruction manual for this unit, however you can find both patient and clinician instructions online easily.  This does not come with a sensor, you must purchase a new, clean, compatible vaginal or anal probes via Prometheus or other vendors, this often requires a prescription.