Patent ID: 7437936

Claim:
A measuring device system comprising: a case of a first measuring device that includes at least three first mating structures; a ring of the first measuring device that includes at least three second mating structures; a non-circular window element that defines an outer perimeter, the outer perimeter including at least three outwardly extending lobes and radially inward recess regions positioned between adjacent lobes; wherein at least the outer perimeter of the window element is sized to rest upon a mounting shelf associated with the ring; wherein each radially inward recess region is configured and dimensioned to allow the window element to bypass the at least three second mating structures associated with the ring; and wherein the at least three first mating structures of the case are releasably secured to the at least three second mating structures of the ring to releasably secure the ring to the case and to seal the window element between the mounting shelf and the case.