This is a pullover knitted in one piece.
It is a loose fit adult size with instructions on how to widen or lengthen the garment based on the provided measurements of the finished garment.
There is a second version holding same ply yarn and knitting the two together with the adjusted needle size to 8mm.
While not knitted in the round circular needles are recommended so that there is greater ease in holding the number of stitches required.
You will also require a 4-5mm crochet hook for the side and under arm joining technique.