I work in a production-line setting requiring constant head turning and back and forth switching between far and near focal points, and these glasses meet my needs just fine in a rapid and rugged environment.
Inexpensive, 100% plastic, and generally durable (the lenses are vulnerable to scratching, hence 4 stars instead of 5, but in this job glass lenses would get scratched as well), their lightweight construction is such that I hardly know I have them on, nor do they fly off my face.
I've tried others and they were simply too fragile or too heavy. I highly recommend this product, and will continue to purchase it on an as needed basis. (review)
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