This pattern works with just about any size thread or yarn and crochet hook, but for the little tiny hearts I love to make, I use a size 50 crochet thread and a US size 10 crochet hook. I also borrowed a pair of magnifying glasses from my mom; my eyes get tired when I make many hearts in a row. I timed myself one day while crocheting in the car (George was driving), and it took me 6 minutes to make one heart. Just FYI.