Patent ID: 8413818

Claim:
A filter unit comprising: a substantially cylindrical body portion having a proximal end and a distal end; first and second recessed engagement surfaces traversing at least part of the body portion, wherein the first and second recessed 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 angle between 50 degrees and 60 degrees from the direction of the first segment; and a third segment that extends substantially orthogonal to the first segment; a laterally extending key member disposed on the body portion between the first recessed engagement surface and the second recessed engagement surface; an engagement protrusion extending from the proximal end and having a sidewall with a water inlet and a concave engagement wall with a water outlet, wherein the engagement wall includes a first portion that angles inward to the water outlet at a first angle and a second portion that angles inward to the water outlet at a second angle different than the first angle, and wherein a periphery of the engagement wall at the first portion includes a first radius of curvature and the periphery of the engagement wall at the second portion includes 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.