Hook size nomenclature

In article , Viktor
wrote:
Maybe this helps:
hook sizes small to large
10, 5, 1, 1/0, 2/0 etc.

The first commercial hooks were made by needle manufacturers - the numbers
are derived from those of the size of needle that was bent to produce the
hook.

Needles don't generally go as big as the hooks neded for conger and shark
so a new numbering scale was added. I don't know what the 'O' stands for
but I always think of it as the letter 'O' for 'Oversize'.

Cheerio,

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