น็อตหน้าแปลน หยัก เหล็ก ชุบนิกเกิล มาตรฐาน JIS

There are two types of flange nuts, one with a serration on the back side of the flange to prevent loosening and the other with a flat surface without serration.

Flange nuts with serrate have the effect of preventing loosening compared to flange nuts without serrate, but damage the components.
Dimensions other than serrate are the same, so decide which flange nut to use according to the application.