"Comprising" means having at least all of the listed elements. "Consisting of" means having all of the listed elements and nothing more. "Consisting essential

"Comprising" means having at least all of the listed elements. "Consisting of" means having all of the listed elements and nothing more. "Consisting essentially of" means having all of the listed elements, with more stuff that doesn't materially change the character of the invention (that's where the lawyers come in). http://www.uspto.gov/web/offices/pac/mpep/s2111.html http://www.uspto.gov/web/offices/pac/mpep/s2111.html