What size is a 6 mm crochet hook?
A 6 mm crochet hook is equivalent to a US J or 10 crochet hook, as well as a UK size 4.
What letter crochet hook is 6 mm?
It's a crochet hook with the letter J.
What size is in mm is a J crochet hook?
It is a 6 mm crochet hook and can also be called a 10 US crochet hook.