M5 m8 m12意思

"M5", "M8", and "M12" are designations used for metric screws, bolts, or other fasteners. The "M" designation stands for "metric" and the following number (5, 8, or 12) indicates the diameter of the screw or bolt in millimeters.

Here's what each designation means:

• M5: This refers to a metric screw or bolt with a diameter of 5 millimeters.
• M8: This refers to a metric screw or bolt with a diameter of 8 millimeters.
• M12: This refers to a metric screw or bolt with a diameter of 12 millimeters.

These designations are used in various applications, including construction, electronics, and automotive. The specific length and thread pitch (the distance between each thread) of the screw or bolt would be denoted by additional numbers or letters following the diameter designation.