Hydor Sintered Quartz Bio-Rings For Biological Substrate Size:400 gm Easily fits over legs allowing

Easily fits over legs allowing freedom of movement

Small grain size and rounded shape for less chance of impaction

When he is relaxed or friendly

If you have a large powerful dog or one that pulls on the lead

moveable D-ring

Hydor Sintered Quartz Bio-Rings For Biological Substrate Size:400 gm Easily fits over legs allowingThe Hydor Sintered Quartz Bio Rings, 450 grams, are an ideal substrate for biological filtration. High surface area and the macroporous structure of the rings facilitates efficient growth of colonies of beneficial bacteria, both aerobic and anaerobic. Bio Rings do not release phosphates or heavy metals and do not effect pH of the aquarium. For freshwater or saltwater aquariums. PH neutral High Surface Area Easy to Use Ideal for optimal biological