you probably want a BV450, it weighs just over 2 lbs and is a good solo container for a couple nights (or more depending on how you pack):

http://www.rei.com/product/768901/bearvault-bv450-solo-food-container

The Ursack is the kevlar bag and is indeed not approved for yosemite:

http://www.ursack.com/

Bearikade is lighter than the BV but significantly more expensive: http://www.wild-ideas.net/products.html