Are vintage crochet hooks sized differently? I have the original

Crochet Hook Sizes - Best Hooks, Types & Charts

BATES, Susan Bates, Red Heart, Silvalume, Inline Aluminum, Crochet Hooks, Size Plus Mm, Single Used Hooks, Made in USA

Crochet Hook Sizes and Comparison Chart - Sarah Maker

Are vintage crochet hooks sized differently? I have the original packaging from the 60's or 70's. It's hero brand & says size i but it's too small to be 5mm. Size 6mm

1930s Crochet - Five Things I've Learned So Far - Vintage Gal

Crochet Hook Sizes and Comparison Chart - Sarah Maker

Crochet Hook Size Guide: Chart, Types & Comparisons for Beginners - Easy Crochet Patterns

Hooks with a History - Boye

Crochet Hook for Miniature Handwork, Thickness 0.4mm, 0.5mm, 0.6mm, 0.75mm, 1mm - Israel

BATES, Clipson, Susan Bates, Steelite Steel, Metal Clip, Inline Hook, Made in USA, Crochet Hook, Single Hook, Steel Sizes 00 Thru 14