Leisure Arts Crochet Pattern, Book

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

Crochet Hook Sizes and Abbreviations (US and UK Terminology)

Boye Crochet Hooks - The Yarn Underground

Boye Crochet Hooks. PICK A SIZE or Make a SET! Aluminum Crochet

Katech Size J/ 6mm Crochet Hook, Ergonomic Crochet Hooks Handles with Soft Rubber Grip for Arthritic Hands, Long Metal Crochet Hooks for Crochet

Boye Crochet Hook 6 Aluminum Size J

Size J Crochet Hook

Boye hooks the wrong size? : r/crochet

The Weekend Cardigan Crochet Pattern

crochet conversion chart to adjustment for crochet for a larger size - Google Search