These are good quality brushes and the sample packet is very, very helpful. I am so glad these folks offer this packet so it is possible to determine needed sizes in advance. Also, a number of interdental brushes have an antibiotic coating which presents allergy problems for many. Since it's a good idea to avoid antibiotics when possible in any case, these brushes are good for that reason as well--they do not include an antibiotic coating that may cause allergy and other problems. Finally, these brushes are manufactured in a precision manner and are quite high quality and sturdy. A study but soft brush is just what is needed. By the way, the regular brush is not too stiff. I avoid stiffer brushes but these brushes are soft while still offering sufficient stiffness. (The company offers a 'soft' set of brushes for those with sensitive mouths -- I doubt most will need these -- the ones here are great.)P.S. For those preferring some type of antibiotic treatment, I should mention I just dip these brushes in a little baking soda before use. The baking soda has an antibiotic effect and also helps clean the teeth and leaves a fresh tast.