does anyone know the dimensions for the spars that go in a peter lynn f-arc 1600

and what are the best materials to make them out of?

My S-Arc1120 spars at 50" seem fit my F-Arc1600

You can make your own ordering parts from: http://www.questoutfitters.com/tent_poles.htm#TENT%20POLES

The 0.433 size is strong enough and fits in arc sleeves.

I found on http://philipbchase.com/assets/documents/arc_setup_faq/ 120cm / 47 inches pretty close to the 50 you posted , the 0.433 is the number I was looking for, thanks for the link:P