The particle size of gelatin determines its dissolving properties. Coarse granulations are slower to absorb water than fine granulations. The water available is evenly distributed, even when the concentration of gelatin is high.
The less stirring that is necessary during the liquid phase (less foaming), the less the tendency for lumps to form and the more the solution must be stirred in order to keep the gelatin suspended. Tailor-Made Gelatin automatically means tailored mesh size.