Also known as pebbles, pebbles (gravel) filter, commonly known as: gravel two kinds of quartz pebbles, gravel cushion, cushion or supporting layer filter media, points (natural) and pebbles (machining). Pebbles are natural river dredging, screening, selected from water, pure white and variegated spherical shape, have a mechanism through processing cobble and quartz gravel. Pebbles, named because of the shape of goose egg. Pebbles as a natural stone, taken from the crustal movement experienced after thousands of years ago by the ancient riverbed gravel ridges produce mountains, experiencing the impact of flash floods, water removal process of continuous extrusion, friction. Tens of thousands of years of tremendous evolution, they tormented waves of water will sport collision friction is lost gravel irregular edges, and they are buried in silt an underground millions of years of silence. Pebbles in the water industry is a filter and filter means necessary cushion, Ningxia Ming Yang gravel filter is a natural river dredging, screening, selected from water, a spherical shape, pure white and variegated colors, quality hard, sharp color quaint, with compressive strength, wear resistance, corrosion resistance properties of natural stone, is an ideal green filter material.