The crown block with sand in water is a patent of that factory.

Limeijia brand factory. Sand-in-water crown spar is a patent of Limeijia brand factory, because it is a new building material with excellent weather resistance and impermeability. Cement, sand and other additives are mixed and poured through a special production process, and after a certain period of curing and hardening, a solid stone is formed. Other factories have not mastered this production process and technology, so they can't produce the same products.