Collapse models aim at describing, whithin one single dynamical equation, both the quantum properties of microscopic systems and the classical properties of macroscopic objects. We discuss the properties of a stochastic differential equation describing the evolution of a free particle subject to space-localizations. In particular, we will see that: a) At the microscopic level the stochastic terms affect in a negligible way the quantum properties of the system: accordingly, the model recovers all know predictions of Quantum Mechanics. b) At the macroscopic level, the wavefunction of the center of mass of a macro-object is very well localized in space and it moves obeying the classical laws of motion.