We've tried many grout brushes over the years, and this is the best we've ever used. Our grout brush measures a full 9 inches in length, and features a unique 45 degree bristle taper that allows it to be used on nearly any size grout line. It is chemical resistant, and can be used with any commercial grout cleaner. Extra heavy duty construction ensures superior cleaning power and a long service life. The brush attachment point rotates a full 140 degrees to deliver maximum pressure and keep the bristles in contact with the grout line. Despite its heavy duty construction and rigid bristles, our grout brush will not scratch soft natural stones or damage healthy grout. Simply put, this is the best grout brush money can buy!