1.For roomba seriesi7 E5 E6 E7 500 600 700 800 900. Easy to clean. 2.Please pay attention to the needle of this style.The needle of this product is pointed, please compare with your original product before buying. If you want to purchase a wheel with a flat needle, we also have it.please look inside the shop. 3.This product is to pass the metal rod through the ball, and then force into the plastic frame. If it falls off, please install it as described above.