Since 2003, the ANSI Standard for eye protection began adding a new rating, or rather dividing the standard in two: high impact (Z87+) and basic impact (Z87).
Z87+ or High impact standard glasses must pass a much more stringent set of tests than the basic or Z87 impact standard.



Z87+ glasses must pass the “high mass” test which consists of dropping a 500 gram pointed weight from a height of about 5 feet onto the lens. It also must pass the test of having a ¼” steel ball shot at the lens. The velocity varies which the product (glasses = 102 mph from a distance of 150′, goggles = 170 mph from a distance of 250′ and 205 mph from a distance of 300ft).



The bottom line is that the high impact standard (the Z87+) offers much better protection. If you are going to wear eye protection it may certainly be worth your while to get the added protection.