Filter system equipped with filter mount and filter inventory

An inventory of filter elements, comprising:

• a first filter element defining a first axis extending away from a first axial end, a first filter medium extending circumferentially around the filter axis, and a first end cap connected to the first axial end, the first end cap including a connector portion having a radial projection, and a first plurality of notches opening at a radially outward edge of the end cap;
• a second filter element defining a second axis extending away from a second axial end, a second filter medium extending circumferentially around the second filter axis, and a second end cap connected to the second axial end, the second end cap including a connector portion having a radial projection, and a second plurality of notches opening at a radially outward edge of the second end cap;
• and
• the first filter element defining a first filter performance factor, and the second filter element defining a second filter performance factor different from the first filter performance factor, and the first filter element and the second filter element being interchangeable for service in a fluid filter system.