also derived from Erik de Bruijn bowden ptfcoupling.
Was never happy with threading a screw onto the teflon toobs. Wasn't reliable, and it just wasn't the way it was meant to be done. I've altered some things to work with 2$ mcmaster push to fit couplings. Been super reliable printing since. I ordered both 1/8" and 1/4" fittings, and am using both, but I like the filament fit of 1/8" more right now.