I have three versions of flat stand-up Wirt display cases, and a more traditional Paul Wirt fountain pen countertop sales display case. Two stand up cases hold 12 pens, and one holds 24. The first Paul Wirt countertop store display case was featured in a 1908 catalog ad, pictured below, and sold with an assortment of Wirt pens. My 12 pen stand-up flat cases are both missing the arms (legs?) on the sides that allow it to stand up tilted back. The 24 pen case has both legs, one broken. It does not appear to be a sturdy design. The first case pictured is top loading and features a pin in the back that locks into a ring at the bottom of the inner portion of the case. The second features a tilt away front. The 24 pen case also tilts open.

This second case is similar, but this model has a front that tilts open to access the pens.

Paul E. Wirt countertop fountain pen sales/display case