This is a monocentric prospective observational study for patients with clinical undetectable breast lesions and indications to breast conserving surgery for histological characterization. The SCOUT® Radar occult breast lesion Localization (SRL) consists of an implantable reflector, a detector handpiece and a console and it uses non-radioactive micro-impulses to guide surgical excision in real time. The study describes the experience with 300 patients at the European Institute of Oncology. The primary endpoints of the study are the rates of successful positioning, localization and recovery of the reflector SRL.