The G-18, G-19 and G-20 are a family of larger flexible filleting knives with the large G series handles designed for heavier work. We recommend these knives for filleting the biggest types of fish, trout, salmon, cod etc where a much larger knife is needed and where something like the G-21 is inadequate. These blades are all really bendy and quite flexible, especially the two larger sizes. The smallest size, the G-20 is moderately flexible and is better for use with meats and can be used as a typical carving knife.