Is the one hundred and ten pound cark stop the only one to use.

well that was informitvie

FilmJumper and DavyG have the best answers for screenplay presentation. I think 65-110 is fine, you don't need 110. You do the front and the back of the script, not the cover page, in card stock. Nothing gets printed on the front.

Card Stock (white or black recommended, can use a color)
Cover Page
Screenplay
Card Stock (same color as front)
Fastened with 3 brads

OR:
http://www.writersstore.com/product.php?products_id=589
http://www.writersstore.com/product.php?products_id=2058

Oh man, I so misread the OP. Sorry about that. I saw it as an ad. Wow, I don't know why.

Script covers - in card stock or “classic linen” - are no longer
used when sending out spec scripts. But don’t tell the Writers
Store, they make a lot of money selling them.

Each agency has their own, printed cars stock covers. So when you
are finally represented your agent will handle that aspect of
your script presentation.

A cover page with the title, your name and contact info is all
that’s needed.