A mixer device for facilitating the formation of turbulence in an exhaust gas stream to enhance the distribution of a reductant in exhaust gases upstream of an SCR substrate to improve NOx conversion and reduce ammonia slip. The mixer device has a first side that is adapted to facilitate turbulence in the exhaust gas stream and a body portion having a plurality of baffle holes and outer layer mixing passages that further facilitate turbulence in the exhaust gas stream. A plurality of protrusions extending from the body portion are adapted to alter a flow direction of at least a portion of the exhaust gas stream to further enhance exhaust gas stream turbulence. Such turbulences may assist in generally uniformly distributing the reductant throughout the exhaust gases, thereby allowing for relatively accurate detection of reductant concentration using a point-measurement device rather than via a more complicated steering wheel probe.
