A Slim Twist is a ballpoint pen that is manufactured by various companies, including high-end accessories designer Alicia Klein. It comes in various styles, but is usually metal or brass with a standard barrel design. If you want to replace an empty ink cartridge you will need to open up the pen. You can then remove and replace the cartridge in a matter of seconds with one of a different color, such as red, blue or black.
Twist the lower half of the pen away from the top half.
Remove the top half; the ink cartridge will be exposed in the lower half.
Slide the ink cartridge out of its compartment and set it aside.
Fit a new cartridge in the compartment. The ink-access end of the cartridge must face down, toward the ball point of the pen.
Screw the two halves of the pen together securely.