Paulson's DK5-X.250AF police face shield keeps liquid from dripping into the helmet, has a hard outer coating and an anti-fog inner coating. This item is NIJ 0104.02 & MIL-V-43511C Certified with a V-50 Impact Rating.
Paulson has many more face shields on its site - http://www.paulsonmfg.com/products/tactical/Military-Police-Face-Shields