If you have a fountain pen with a converter you have probably noticed that you never can fill them all up in a non messy way. I spend years trying to figure it out. If you wonder why I would care about it, it is just that with most converters it's like 25-30% that is empty. There are situation where that difference are the difference between running out of ink before the day is over or not. If you use a syrringe you can fill it all the way up in seconds.