The Motiva® Sizer clinical study is a four-year, multicenter, post-marketing, and cohort study, designed to confirm the safety and performance of Motiva® Sizer in breast augmentation or reconstruction procedures. The research will include 330 women, divided into two groups of 165 participants each (150 breast augmentation participants and 15 reconstruction participants). The Motiva® Sizer exposed group will consist of women who will undergo breast augmentation or reconstruction surgery with the use of Motiva® Sizer during the procedure, and a non-exposed group will consist of women who will undergo breast augmentation or reconstruction surgery without the use of Motiva® Sizer. This study will be conducted in Costa Rica. The main goal is to evaluate the safety and the performance of the Motiva® Sizer. To this end, the results of both groups will be compared in terms of surgical complications, surgeon's, and participant's satisfaction level as well as reoperation rates. After the augmentation or reconstruction surgery, participants will be scheduled for the following follow-up visits, (1) between 3 and 7 postoperative days, (2) between 3 and 6 postoperative weeks, (3) at 3 and (4) 6 postoperative months, and (5, 6 and 7) annually thereafter for a period of three consecutive years. In case any participant has an adverse event due to the procedure, and if required by the physician, an additional visit will be made to assess her, and this information as well as that of the scheduled visits should be recorded in the electronic data collection notebook.