What is meant by with or without Scrim? what are the pros and cons of the two besides the price? thanks

As it was explained to me the scrim is a layer of glass fibers running 90 degrees the length of the glass.  The benefit, the glass is less likely to crack when drilled for limb attachment bolts etc. Have heard the clear with scrim isn't quite as clear as regular.

I used ULS.. scrim glass on a bow once over dark veneers..in the bright sunlight you can see the fiberglass 90* scrim..does not look too bad and it does not bother me..I have to look close to see it.

It aids in preventing limb twist.   I use it for recurves but not on my longbows.