When ordering fiberglass from Binghams, there is the option of with or without scrim.
What is the scrim and what difference does it make?

I'd like to know as well.  I ordered mine from 3Rivers and was very pleased with it.  I'm curious to what they classify that as.

scrim has a unidirectional fiber inside the glass mix, suppose to make it more stable.
  the ul glass does not have this.
   I have used both and the only thing i see different is the price

This is from binghams. I think without scrim is not as stiff laterally. Im not sure what if any impact this has on bow performance. Might be better in a recurve, since the limb tip "roll out" is effected by limb width.Maybe someone with experience with both products will chime in.
Hope this helps.-Greg

"Gordon Bo-Tuff E Glass ULS

A continuous unidirectional "E" fiberglass combined with a 50/50 woven fiberglass inlay (scrim) that has high strength and stiffness along the longitudinal (0) axis and provides cross strength (90 degrees to the longitudinal axis)."

I've only built longbows but I agree with Shaft slinger. I've tried both and didn't see any difference in the type of bows I build.