Tough as Nails. The name says it all. Steel Flex liners pack more performance into every bag, providing up to 50 percent greater puncture and tear resistance than other low density liners. Tough as Nails. The name says it all. Steel Flex liners pack more performance into every bag, providing up to 50 percent greater puncture and tear resistance than other low density liners. That means a lower gauge Steel Flex bag will perform as well as, or better than, the more costly, higher gauge bag you may be using now. Best in class Steel Flex liners are a strong Green source reduction choice, too. Thanks to thinner, stronger films, Steel Flex liners can cut plastic waste by up to 25 percent compared to thicker, lower performing bags. Steel Flex liners work in a variety of applications. They are recommended whenever maximum puncture and tear resistance are required.