德国博世激光测距仪DLE40

锌钢护栏成为冬奥会建设的助力军

As soon as he had spoken, the Tin Man began to chop, and in a short time the tree fell over with a crash, whereupon the Scarecrow's clothes fell out of the branches and rolled off on the ground. Dorothy picked them up and had Winkies carry them back to the castle.

光纤滑环是什么，起到什么作用？