The Seachem Aquarium Scraper is designed with versatility in mind With three retractable blades metal plastic and soft pad it is suited for both glass and acrylic aquariums It is lightweight and features an ergonomic handle making it comfortable to hold in multiple positions In addition it floats for easy retrieval. Finally its white color makes it easy to see the algae you want to remove and when you've effectively removed it Metal Easily removes tough algae in glass aquariums Not for use on acrylic Plastic Safe for use on glass and acrylic Use care at gravel line to avoid scratching acrylic Soft Pad Your first choice for acrylic aquariums Easily removes gunk from scratches