Features: Great adsorption material to make your water clean and no pollution efficiency. Perfect for removing chemicals from your aquarium: foul odors, heavy metals, yellow discoloration,etc. And keeps tank water crystal clear Activated carbon has a strong physical adsorption and chemisorptions role in the adsorption of organic compounds. Works faster, better, and long life usage, to restore greatest water quality to your fish. More efficient than coconut, wood, or peat-based carbons. Package included: 250 gram Activated Carbon Notice: 1.Please allow 1-3mm error due to manual measurement,Please make sure you do not mind before you bid. 2.The colors may be a little difference for the different monitors displays, please understand.