"Clamp Type" knee switch which don't need to cut the table, drillinghole, install by screw. It's easy to fix them up.
“卡钳式”膝动开关，无须切割桌板、钻孔、装订螺丝，安装容易、简便。
2
The first drillinghole of the Wenchuan earthquake fault science drilling project (WFSD-1) experienced up to more than 30 meters of the fault gouge drilling process.