The aluminum he chose was 6061 Aluminum Alloy. To be more specific, 6061-T6 Aluminum, a tempered grade that has been heat-treated and aged to add a significant strength element. The Sling uses all traditional AN Hardware in its construction, meaning it lives up to the US Air Force/Navy Standards. Solid rivets are used on the main spars, which are standard aviation type spars with our own unique design for added strength, and pull rivets for the rest of the structure, making construction a bit easier while maintaining structural integrity. The Airplane Factory uses high quality rivets manufactured in Germany that are well known throughout the aircraft manufacturing industry. Composites are also used throughout the airplane where appropriate, for example, cowling, fairings at the wing roots and the intersection between the vertical stabilizer and the fuselage, wheel pants, as well as the instrument panel and canopy structure. For reduced weight but added strength, the landing gear is also composite construction which can take a heavy amount of stress regularly without issues.