Spacepen Minen universal SUx

 The SU Cartridge is the skinny one on the top and bottom. When it arrives
it will be long like the top image shows.  It is made this way to fit several different pen barrels.  If you need
it to be shorter, just flex it back and forth at the break point and it will separate, leaving you the correct length.

The PR and SU Cartridge are NOT INTERCHANGEABLE!