The M-D Building Products SmartTool family is one of the pioneers in 360 degree angle measurement. Beginning in 1987, Wedge Innovations, invented, developed, manufactured, and marketed the custom liquid inclinometer used in the SmartLevel electronic digital level, sold through professional tool retailers worldwide. In 1992, Wedge was purchased by M-D Building Products, then Macklanburg-Duncan, a leader in contractor grade levels. For the last 25 years M-D has continued to grow the market for electronic angle measurement and is the market leader in this technology. Still the most accurate, affordable, inclinometer sensor in digital levels today, it is made in the M-D Building Products Headquarters in Oklahoma City, Oklahoma.