S-350 and the S-420 are the most popular products of Capstone Series. S-420 features the high quality and high strength concrete test capping material. It is designated as the most reliable product by many professional testing labs. The high reputation of S -420 raised the demand. Modern buildings such as high-rise construction request S-420 as the minimum strength as qualification.

The water to gypsum ratio for S-420 is recommended to be 21-22%. After simply mixing with water, the gypsum is ready to use immediately and will be fully solidified after approximately 30 minutes and reach the strength over 420 kgf/cm2, Equals to 6000psi.