I was given a Sensa black zephyr pen. I replaced the cartridge with the same thing that was in it (Fisher Space Pen pressurized) and it works fine. It is in it's original black box with red penstripes and the Sensa logo. The pen is also inside a foam case that has the Sensa logo on it. People at Goldsppot told me the foam case is unusual and might be worth some $$. IDK. I am just needing some help researching it. I have been all over the Internet and can't find a Sensa pen anywhere that came in a foam box inside the regular box. Hope you can help me with this. Thank you.