Patent ID: 8356716

Claim:
A filter unit comprising: a substantially cylindrical body portion having a proximal end and a distal end; first and second engagement surfaces traversing at least a part of the body portion, wherein the first and second engagement surfaces comprise: a first segment that extends substantially parallel with the longitudinal extent of the body portion; a second segment that extends at an acute angle relative to the first segment; and a third segment that extends in a direction different than the first segment and the second segment; a laterally extending key member disposed on the body portion; an engagement protrusion extending from the proximal end of the body portion and having a sidewall with a water inlet and a concave engagement wall with a water outlet, wherein a periphery of the engagement wall includes a first portion having a first radius of curvature and a second portion having a second radius of curvature that is larger than the first radius of curvature; and first and second seals disposed about the sidewall, wherein the water inlet is disposed between the first and second seals.