Well Caps are compression molded with smooth inner and outer surfaces to a uniform thickness of .430" on top and rim is .350" with a 1 3/8" inch crown on top. SRC (Sask Research Council, an Independent Testing Company) rated maximum vertical load of Cap to be 57640 lbs. Well Cap is secured with self tapping screws anywhere on pipe except on the small belled end. If you would like to view a copy of the SRC report click here (pdf).