Terrific "eyedropper" style solution for C/C pens
These are reinforced, free-flowing ink cartridges that can be used multiple times and are stronger than the standard cartridges. They give you a mini-eyedropper style feature in your Sailor pen. The wide mouth opening makes them easy to refill, and they have a great capacity that is up there with many piston filling systems. They are also more efficient with ink usage since you are not wasting ink on the nib that you wipe off when filling from a converter.
However, they are stiffer, and therefore, you should not try to squeeze them to "prime" your feed.