ss manhole YAA With or without pressure Size: 350*90mm 20 years specialized manufactuer Type:Squareness,Roundness,Oval,Hand Hole Cover Material: 304,316L,321,304L,316Fineness: inner and outer fineness of mirror Ra≤0.8μm,inner and outer mechanical polish and electrical polish Ra≤0.2μm,external surface can be gross polished or sub-gross polished. We are specialized in producing different kinds of ...