Cap Neck Finish Guide
8mm caps and closures include 8-425 thread finishes.
Caps and closures are measured using two numbers in the format of 8-425 or 8/425: the first number is the distance in millimeters from outer thread to outer thread when looking at the top of the container; the second is a reference to the design of the threads themselves. Review the image to the right in order to understand thread design, to assist you in selecting the correct cap for your bottle or container. Carefully review your container's threads before selecting a cap even if you know the first measurement; not all 8mm caps will fit a 8mm opening, due to the differences in thread types between manufacturers.