Patent attributes
A filter unit includes a body portion having a proximal end and a distal end and a shoulder disposed therebetween. An engagement protrusion extends from the proximal end. The engagement protrusion includes a sidewall with a water inlet and an engagement wall with a water outlet. A cross-section of the engagement protrusion taken orthogonal to the longitudinal extent of the filter unit has only one axis of symmetry. A first engagement surface traverses approximately one-quarter of an outside circumference of the body portion. A second engagement surface traverses approximately one-quarter of an outside circumference of the body portion opposite the first engagement surface. A laterally extending key member is disposed on the body portion proximate the shoulder. An electronic device is positioned on the body portion adapted to store usage information relating to the capacity and usage of the filter unit.
