I have been experimenting with several different sizes and types of tubing. I have made GM and push-on ends, as well as single and double flare fittings. My only issue has been working with harder materials. The tool is designed for use with soft (copper/aluminum) tubing but the hydraulic press is more than capable of dealing with steel. The problem is that the dies can't grip steel lines tightly enough and may slip if used with hard metals. I believe this can be made to work by modifying the dies but that is a work in progress. I recommend this for HVAC work.