106-5012 S Size 15kg
106-5011 S Size 8kg
106-501 S Size 2kg
106-5022 M Size 15kg
106-5021 M Size 8kg
106-502 M Size 2kg
106-5042 LL Size 15kg
106-5041 LL Size 8kg
106-504 LL Size 2kg
106-5032 L Size 15kg
106-5031 L Size 8kg
106-503 L Size 2kg

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.