Safe for Glass or Acrylic Aquariums Patent pending design allows you to use any old credit card, gift card, hotel room key etc as a scraper blade....you may never have to buy blades again! Blade cards can be inserted in any direction for multiple levels of flexibility Cut your own custom blade card shapes for cleaning difficult curved or tight areas of your tank Solid fiberglass matrix handle is practically indestructible! Handle grip will vary between orange and black