Hi Yangshun, those are called Rastex. You can find more info about this screw in this document: www.hettich.com/fileadmin/content/mediathek/HUS_174_185.pdf. Look in pg no 175. Good luck!
Hi Chanaka, those are called Rastex. You can find more info about this screw in this document: www.hettich.com/fileadmin/content/mediathek/HUS_174_185.pdf. Look in pg no 175. Good luck!