ELM327 mini adapters are smaller and more convenient to use than their larger counter-parts. These devices include the same hardware within the device however the circuitry is arranged differently to fit into a smaller space. Because of their smaller size and lighter shell, these can sometimes be cheaper than their counter-parts because of savings during shipping, as well, may be more convenient to use as they are less likely to get in the way while plugged into an OBD2 port.