... reliably measures the thickness of the poured concrete slab of non-metal like structure,concrete,wall,girder,bar,pole,wood and ceramics ... ×80mmExtension Bar:φ25×600(mm)(3 piece)Work PrincipleDJLC-A concrete thickness gauge is composed of signal transmit, connector, signal ... without analysis also can be stored or printedSpherical direction conniction used,0-180 degredd adjustment are available