For this design you can use 4ply sock yarn or any other 4ply yarn, so the bootees can be knitted for a boy or a girl. You can leave the cuff up (as in the photo) or fold it over. They will fit baby feet up to 3.5inches (9cm). My baby girl tested them while kicking about in her bouncer chair. Please let me know your comments & take a look at my website for more creative stuff - www.adelsknitandcraft.wordpress.com