Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <HomerLea-at-aol-dot-com> I have a pile of roller bearings 1 1/2 inch high and the same diameter. I have thought of lining some up to use for a spark gap. Has anyone tried this type of material? If not maybe someone will try them at the N.Cal. Teslathon. jim heagy