Knockout Drain Unblocker is for use in toilets and outdoor drains. It's specially designed to rapidly clear blockages in outside drains, pipes, and toilets. This product is industrial strength, making it suitable for trade and professional use. Wear protective clothing when using. It's not recommended for use with septic tanks. The formula is designed to clear fat, grease, and hair. It can be used in kitchen, bath, and shower drains. The product comes in a ready-to-use formulation and is available in a 500ml size.