An air cleaner assembly comprising: a housing comprising an exterior surface around an interior volume , the housing comprising: a bore extending through a portion of the exterior surface of the housing along an insertion axis and surrounded by a bore wall protruding from the portion of the exterior surface along the insertion axis ; and a receptacle wall around the bore wall along the insertion axis and radially spaced from the bore wall to form a channel between the bore wall and the receptacle wall; and a restriction indicator configured to measure a restriction in the interior volume when coupled to the housing and to display an indication of the restriction, the restriction indicator comprising: an indication element configured to display the indication of the restriction; a stem at least partially insertable into the bore along the insertion axis and configured to engage an inner surface of the bore wall when disposed therein; and one or more tabs at least partially insertable in the channel between the bore wall and the receptacle wall and configured to facilitate removably coupling the restriction indicator to the housing, characterized in that the receptacle wall protrudes outwardly from the exterior surface , and each tab is deflectable to couple or uncouple to the receptacle wall . a housing comprising an exterior surface around an interior volume , the housing comprising: a bore extending through a portion of the exterior surface of the housing along an insertion axis and surrounded by a bore wall protruding from the portion of the exterior surface along the insertion axis ; and a receptacle wall around the bore wall along the insertion axis and radially spaced from the bore wall to form a channel between the bore wall and the receptacle wall; and a bore extending through a portion of the exterior surface of the housing along an insertion axis and surrounded by a bore wall protruding from the portion of the exterior surface along the insertion axis ; and a receptacle wall around the bore wall along the insertion axis and radially spaced from the bore wall to form a channel between the bore wall and the receptacle wall; and a restriction indicator configured to measure a restriction in the interior volume when coupled to the housing and to display an indication of the restriction, the restriction indicator comprising: an indication element configured to display the indication of the restriction; a stem at least partially insertable into the bore along the insertion axis and configured to engage an inner surface of the bore wall when disposed therein; and one or more tabs at least partially insertable in the channel between the bore wall and the receptacle wall and configured to facilitate removably coupling the restriction indicator to the housing, an indication element configured to display the indication of the restriction; a stem at least partially insertable into the bore along the insertion axis and configured to engage an inner surface of the bore wall when disposed therein; and one or more tabs at least partially insertable in the channel between the bore wall and the receptacle wall and configured to facilitate removably coupling the restriction indicator to the housing, <EOS>