They are easy to install. Look like those who have bought in the past. THEY GO NO FURTHER. I went through many of them before it was time to change. The last one only lasted 2 weeks. The use is the same, the environment is the same, so the only thing is the product. REVISED FOR TODAY MORE BRUSHING REFUSED. GET BEST ONLY APPROX. 28% BEFORE REPLACEMENT. WASTE OF MONEY.