These are crafted from brass/copper tubing and tuned to open D or E. The F#(G#) string lowers a half of a step making a minor chord with the knee lever. They have bearing rollers on the nut and bridge so they have good tuning stability.
Timothy, I was wondering about your thoughts on the difference in sound and tone not having a body.
When I worked for Robert Randolph, he had a Harmos lap steel that didn't have a solid body or thick neck:
I remember it had a thin sound that was delicate and appealing.
I'm guessing a reduction in weight was a factor too.