I am a machinist and wear safety glasses all day every day. I've tried many different brands over the years and in my experience these are the best I've used. They are lightweight and don't squeeze the area over or behind the ears. They stay in place nicely without falling forward. They are bifocal where the split line is well placed, I don't need to tilt my head back to read the monitor.
I am very pleased with these and I highly recommend them to bifocal and non-bifocal wearers.