It is natural river gravel. Unlike sea gravel, you do not have to worry about hardness increase.
There are 4 size variety, S, M, L, and LL. S size can also be used as substrate material like Oiso sand. M-LL size can be mixed together, and used for promoting riverbed aquascape.
This hardness is free shrimp gravel water neutral, light and CO2 resistant. It is used fish-keeping. The gravel is rounded and has a grain size of 0.7 to 1.2 mm.
Pollutant-free shrimp gravel with rounded grains for a minimal risk of injury. Does not change the water values due to its water-neutral and CO2 resistant texture.
Aquarium gravel ideal for shrimp tank and other aquariums. It is used for fish-keeping. This is safe for shrimps and crabs. It is CO2-proof and water neutral. Available in yellow colour.