Diamond H Company, LLC, was formed to develop the concepts embodied in the Quick 220 Voltage Converting Power Supply. The first model was made available to the public and sold in 1998. In 1999, United States Patent 5,977,658 was issued covering the safety circuit employed within the Quick 220 Power Tap. Diamond H manufactures the Quick 220 Power Supply in Phoenix, Arizona, USA. As a company, we are committed to supplying a high quality product supported with a high level of personal service.