BEST AQUARIUM GLASS CLEANING TOOLS:Razor blades are the quickest and most effective way to clean your aquarium, Perfect for cleaning the most stubborn algae like green and black algae without scratching your glass, leaving your tank looking brand new. New design: wide handle is better for gripping, with small round hole at the end, you can hang it up when you are done using it, and the head of the knife comes with a protective cover for easy storage. EASY INSTALLATION:You only need to loosen two screws to install the blade, you can refer to the installation instructions on the back of the box, if you have any installation problems, please feel free to contact me for guidance. LOW COST MAINTENANCE: Comes with 10 replacement razor blades, we offer more razor blades which can be purchased by searching "SWETOR Algae Scraper Blades". EASY TO HANDLE:The lightweight structure can reach into the narrow space of the aquarium to clean, the perfect length won't get your hands wet. (Suitable for both freshwater and saltwater tanks)