2-1/2″ diameter vacuum gauge. Dial improved accuracy to asme b40.1 grade a. One piece design for toughness during installation. Glycerine filled for added durability during in application. Stainless steel case and bezel with copper alloy internals. features 0/6000 psi stainless case brass internals 1/4″ npt lower mount glycerine filled pressure gauge polycarbonate lens ambient temp 30 f to 160 f