It does not have and brings about that there is pit on revetment brick thanks to nut protrusion.During the present embodiment, the amount of counterbore and fixation gap is not constrained Other options and advantages of the utility model will illustrate inside the following description, also, partly from specification https://production-equipment-for51593.blogitright.com/33657943/top-box-type-slope-protection-mold-secrets