Sigmatek Systems International provides internet services, including data subscription and instrument sales, in Bellevue Washington. The company offers a range of products for navigation systems, air traffic control, and military applications. Sigmatek's instruments are known for their reliability and quality, with the Sigma-Tek 5000B AI and 4000B DG being among the most popular options. With products available in various voltage configurations and built-in diagnostics capabilities, customers can choose the right instrument to meet their specific needs.