Hex nuts are the most widely used nuts and will work for most applications.
Size: M4-0.70, Stainless Steel, Not Graded, Plain, 25 PK They are standard thickness and can be installed with a wrench or socket set. Machine screw nuts, is a subset of finished hex nuts designed for use with machine screws, which are typically much smaller than bolts.70Very common and versatile nutSame in design as a standard hex nut, but smaller to accommodate machine screw sizesScrews onto a machine screw of the same thread sizeOften used with a washer with same diameter openingThread Type: Coarse, Thread Class: 6HSpecification(s) Met: DIN 934.