EKULF pH professional 0,4 mm interdental toothbrush is the smallest size in the series and can be a good size to start with. EKULF pH professional is developed according to the Swedish pharmacies color-coding for interdental toothbrushes to make it easy to recognize your specific color and size. The series maintains the same high quality as EKULF pH with 400-1000 small and delicate bristles and has a stainless, plastic-encased wire that protects your teeth. Each packaging is delivered with a protective cap and a grip-enlarger. An interdental toothbrush should never be forced in between the teeth, but rather glide easily.