The Euro-Format Rollerball Refill is a universal style refill which fits approximately 80-90% of all capped rollerball pens on the market. There are some small varatiations in Euro Rollerball Refills however, like a small shoulder step, and they are not all created equal meaning some don’t fit in some pens. We would recommended going for the branded refill you require as a rule of thumb with these ones but if your happy to take a chance, which will more than likely fit, there is a great deal of options for colour.
If the refill you have is Euro Refill you have is unbranded and safe bet would be the Schmidt 888 as many pen manufacturers use Schmidt refills in their pens for their quality and writing excellence.