Supports the following standards: BS EN ISO 9001:2000, ACI 2242-01 The crack width gauge is designed specifically to measure widths and locations of cracks prior to beginning a monitoring program. The crack width gauge is suitable for internal and external use. It is made of polycarbonate, which has a coefficient of linear thermal expansion of 7.0 x 10-5 cm/cm/°C for ambient temperatures between -30°C and 30°C. The scale is calibrated from the end of the gauge to facilitate measuring cracks in corners. Supplied in protective case.