willembad,

The extra in the pic is a 32% 3W extra.

I thought of the jam nut idea, I use them on any setup with clevises (plastic or metal). As for the square nuts on the rocket city horns, shouldn't that have been thought of by the manufacturer by now? I mean that's an obvious flaw in the design. So if anyone with friends in high places is reading this: instead of molding a square hole in the horn, mold a hex hole and provide a nyloc nut. I'll be looking for this modification on later models.

Ben