Check out a great piece on Shore Hardness here and the variation in flexible materials.

Would you like your 3D models to stand out by their elasticity and flexibility but you could not find a suitable elastic material that would fulfill your idea? We have a solution - try printing flexible parts with Flexfill TPU 3D Printer Filament by Fillamentum. And if you have a printer with two print heads you can use Flexfill TPU to add an extra layer which will make a surface soft to touch.