A little-known fact about the Kaweco Sport rollerball pen is that the refill inside is exactly the same size and shape as a common size of ballpoint pen refill.
On the right, we've a red Kaweco Sport rollerball pen with its black Kaweco rollerball refill. On the left, we've the same red outer casing but with a blue ballpoint refill. We call these ballpoint refills Parker-style refills after the most famous manufacturer of this style of refill. We stock the Parker refills and also cheaper versions by Schmidt, and Schneider. We also keep the gas-pressurised ballpoint refills for the famous Fisher Space pens which come with a little gizmo to pop on the end that means they too mimic this style of ballpoint refill, but with the added bonus of enabling you to write upside down on the ceiling with them, on wet paper or in the zero-gravity of outer space.
With the Kaweco Sport rollerball pen you can have your cake and eat it. If you prefer the stronger colour and an ink that more closely resembles fountain pen ink, you can stick with the Kaweco rollerball refill that comes as standard with this pen. If you hanker after the stickier ballpoint pen ink that is less likely to show through to the other side of your paper, then choose a Parker-style ballpoint pen refill. We usually keep red, green, black and blue in stock.
A little-known fact about the Kaweco Sport rollerball pen is that the refill inside is exactly the same size and shape as a common size of ballpoint pen refill. 
On the right, we've a red Kaweco Sport rollerball pen with its black Kaweco rollerball refill. On the left, we've the same red outer casing but with a blue ballpoint refill. We call these ballpoint refills Parker-style refills after the most famous manufacturer of this style of refill. We stock the Parker refills and also cheaper versions by Schmidt, and Schneider. We also keep the gas-pressurised ballpoint refills for the famous Fisher Space pens which come with a little gizmo to pop on the end that means they too mimic this style of ballpoint refill, but with the added bonus of enabling you to write upside down on the ceiling with them, on wet paper or in the zero-gravity of outer space.
With the Kaweco Sport rollerball pen you can have your cake and eat it. If you prefer the stronger colour and an ink that more closely resembles fountain pen ink, you can stick with the Kaweco rollerball refill that comes as standard with this pen. If you hanker after the stickier ballpoint pen ink that is less likely to show through to the other side of your paper, then choose a Parker-style ballpoint pen refill. We usually keep red, green, black and blue in stock.
