Double disc single speed metallographic sample pre mill M-2 is a wet grinder, it USES the different size of the metallographic sandpaper, on a variety of metal and alloy samples.

双盘单速金相试样预磨机m - 2是一种湿式磨光机，它利用不同粒度的金相砂纸，对各种金属及合金的试样进行磨光。

youdao

It's as if the folks at Nintendo took sandpaper to every edge of every disc, making them all the more friendly to the touch.

ENGADGET: Take a very, very close look at the round-edged Wii U proprietary discs