The Polilock fixator is a radiolucent external fixator intended to stabilize fractures in small dogs and cats. In its basic frame configuration, i.e. single connecting bar and 2-3 pins for each fracture segment, the patient's weight should not exceed 5 kg. As usual for external fixation, the addition of pins, connecting bars, and changes in the frame structure may profoundly affect the biomechanical properties of the fixator, allowing its use in heavier patients. Being almost impossible to describe all the potential variations of the fixator features that are able to change its biomechanical properties, it is the surgeon's experience that dictates the patient's weight that fits a specific frame configuration. Nevertheless, in the following technical suggestions examples of the fracture reduction strategy and frame configuration will be given for user's orientation.