Sur-Lock Frac Fluid Ends come with the Sur-Lock Quick-Change Valve Cover. The fluid end is designed with the valve cover “threads” machined directly into the valve body. The valve cover drives straight into the body with an impact wrench or pneumatic torque wrench. Typically a valve cover can be removed or replaced in seconds rather than minutes. Additionally, the valve cover can be torqued and pre-loaded to exact specified levels, thus preventing wash-outs from using other less-precise methods.