Developed from a proprietary mixture of ball clays fired to a ceramic body. Pinkish-tan in colour, moderately hard and will withstand pressure differentials of 15 Bar (217.5 psi). Typical bubbling pressure: 220 psi. Effective pore size: 0.16 micron. Hydraulic conductivity: .00000000259 cm/sec. Approximate porosity: 32% by vol. Flow-through