I have used these Ergo Loupes for more than one month. They soon became my favorite loupes in surgeries. They are extremely light of weight, bright and clear. More importantly, I do not have to bend my neck during surgeries anymore. The magnification of Ergo 4.0 in 550mm is close to the magnification 2.5 of my traditional Galileo in 450mm, so I get used to them without much efforts. Wise investment of my 2021.