BellaOnline Forums Hobbies and Crafts Crochet need help understanding pattern

I found a pattern for a granny square that was originally written in Spanish and translated into English. The instructions don't seem to be complete. The pattern only tells you to use a steel hook No. 4 and I've looked at several conversion to try and figure out what letter that hook is. One conversion chart said that the No. 4 was a 2.0mm hook. The pattern also does not tell you what size yarn to use. I can only go by what the pattern looks like and guess what size it is. I'd like to make granny squares and join them to create a table runner for my mom for mother's day so I'd like to start on this pattern as soon as I can. Any help would be appreciated.

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A steel hook is very tiny, and those hooks don't go by letter, but rather the number and the mm size. Most granny squares are used to make afghans, but since you want to make a table runner, you may want to use a fine cotton that requires a small hook anyway. BTW, you can get non-steel hooks as small as size B and C, which are equivalent to 2.25mm and 2.75mm, both of which are larger than a number 4, which is 1.75mm, according to the site I looked at (it said number 2 in UK conversion, which you should ignore, unless you live in the UK)