Bottle Neck Sizes Explained: 18 mm, 20 mm and 24 mm Caps, Pumps and Droppers (What 20/410 Really Means)
What 20/410 and 24/410 mean, how to measure a bottle neck, the difference between 400, 410 and 415 threads, and real per-piece prices for 28 Zenvista caps, pumps and droppers by neck size.
