Traditionally and since the start of their use in oncology research, the volume growth of xenografts or subcutaneous tumors in small rodents has been monitored by using a traditional mechanical caliper. Technological evolution and the increase in computing power have facilitated the development of new devices such as the Peira TM900, https://www.peira.be/measuring-device-oncological-tumor-research . It is a lightweight handheld instrument that makes a direct 3D measurement of the tumor volume by acquiring a stereoscopic image and reconstructing the 3D shape of the tumor. This allows a direct 3D capture of the volume. A tumor image, its 3D shape and all geometrical data are automatically calculated and stored. Database, data management and processing software are included. The system can be complemented with a weight scale.