Whether you are looking for teardrop or round shaped implants, find your ideal width, height, volume & projection Breast implants are normally measured by volume and not cup size. NATRELLE INSPIRA COLLECTION chart of projections. Sizes, dimensions and projection measurements for Allergan Natrelle silicone gel breast implants; warranty information. Consult Allergan - Natrelle's entire Product Catalog catalogue on MedicalExpo. to evaluate and assist in determining the final breast implant size/volume.