No, that little number Z87 on the inside of the arm of your safety glasses is not the part number (We get at least 2 or 3 calls a month from customers who give us the Z87 number, believing it to be the part number of the glasses that they are holding), it’s the number that lets you know that the glasses you are holding are rated and pass the Z87 standard from ANSI for eye protection.
You may have noticed, however, that recently the Z87 sometimes has a little “+” sign after it. What does that mean?
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.