We have two back brushes. The one in the guest bathroom is glorious, with bristles hard enough to rip your skin off. The one in our bathroom, on the other hand, is so soft you could polish silver with it. Sadly I only think about switching them when I am in the shower. A whole year later the back brush in the guest bathroom finally made the 50-ft journey to our bathroom. That is 0.000001 miles per hour.