Sizes: 3-6 months and 12-18 months. Finished Chest: 17 [23 1/2] in. or 44  cm Finished Length: 9 1/2  in. or 24  cm BASIC SKILLS NECESSARY Stitches used: ch " chain stitch; dc " double crochet; hdc " half double crochet; sc " single crochet; sl st - slip stitch SIZING / FINISHED MEASUREMENTS 3-6 months and 12-18 months. If you want to make this vest in size newborn-3 months, I would suggest to use instructions for 3-6 months, but to work with sport weight yarn, and if you want to make it in size 9-12 months, use instructions for 12-18 months, but work with sport weight yarn.