if Im understanding U right, poly fittings are plastic, and with them, an IDIOT warning should some with them. They are plastic. and with any plastic, to much force will crush them. A snug fit on a hose clamp should do fine, Dont crank them down.
A brass fitting, is well.... brass, harder material, U can smash a hose on them. Which will make it a bear to get back off. I have been looking into poly fittings, I love them, they are not as bulky, or that ugly brass color.
But like I said, Poly fittings should come with a warning, Cause U know someone (prolly me) will crank the hose clamps down way to tight.
