Crook's first invention, the Flex Flow Elbow®, was inspired by a commercial job he completed in Kansas City some time ago. The mechanical engineer on the job required elbows on all 1,000 diffusers as per specifications. Providing sheet metal adjustable elbows was expensive and labor intensive. Adding to the complications, many of the elbows called for were different sizes. At about $20 each - including labor, sealant, and insulation - the total bill came to approximately $20,000.
The inspired Crook came up with a better way. The Flex Flow Elbow he invented was two years in the making. Crook and Thermaflex, the manufacturer, describe the product as an adjustable band that fits any brand and any size flexible duct from 6 to 16 inches.