Some lens has a protective point, this point is a measure for anti-static burn of a and keep its safety , as our clothes and hair are all static materials, you can open this protective point with an high-grade anti-static iron, if you use a common iron, it requires much special attention, first, if the iron has melted the tin-can temperature, do remember to unplug the iron supply, then go to open the lens protection point, this is to prevent lens from burning by static electricity iron.