These refills are designed for my Slimline Pens. You can choose from either black or blue. To install, simply pull the top half of your pen off, unscrew the existing cartridge, and screw the new one into it's place. If the nib projects too far past the top of the pen, simply screw the refill out slightly.
Please share your experience with Webster's Wood online, and be sure to tag @websterswood.ie on Instagram and Facebook.