Oyster Shell Mix, Oyster Shell, Calcium, Bore, Borei Please let us know before purchasing if you are a repeat customer. I am also selling the same item on Yahoo Flea Market. This is a mixture of oyster shells, powdered to about 4mm. Powder accounts for 30-40%, and 0.5-4mm accounts for 60-70%. 150 grams is about 150ml. We have plenty of stock, so if you need more than 150g, please comment before purchasing. We will add 30 yen for every 50 grams increase. Please inquire for discounted prices depending on the quantity. We also sell by grain size. You can select the grain size from 0.5 to 7 mm, in approximately 2 mm increments, so please comment with your desired size. Also, we can provide samples of coarse, powdered, and fine grains as a trial, so please comment. De-salted, then heated and dried at around 500 degrees Celsius for sterilization. The main component of oyster shells is calcium carbonate. For calcium supplementation for small birds and chickens. For adjusting the acidity of horticultural soil. Since powder is mixed in, it may be a little difficult to use for aquarium filter media, etc. Raw materials: Oyster shells (made in Miyagi Prefecture) Alkaline content 50.0% Nitrogen...0.2% Phosphoric acid...0.15% Potassium...0.03% Calcium...94.8% Magnesium...0.40% Silicic acid...3.09% Other trace amounts of manganese, boron, zinc, copper, iron, molybdenum, etc. Shipped via Yu-Packet Post Mini. When used as feed for living creatures, there is no expiration date or best-before date for oyster shells, but please use them within 2 years of opening as a precaution.