Refills for your Sensa ballpoint are slightly different based upon the age your Sensa. Please compare your Sensa ballpoint refill to those shown and you should easily see the difference.
The older style Sensa uses a pressurized Fisher ballpoint refill.
The newer style needs the Parker-style ballpoint refill shown. Parker-style ballpoint refills are offered in three ink types, pressurized or not, and ten different colors, all from a large range of manufacturers. Select from standard ballpoint ink, liquid ink or gel ink. You can choose from fine, medium or broad points.