in the u.s. they only come in bantam, all r bantam but some r on the large size. if u see giant silkies they r a mixed breed. chinese silkies r normal silkies.
silkies r the bombs of mothers they will hatch anything u put under them includeing a rock or air,lol they r very deturmined mothers. if u put standard eggs under the bigger they r the less eggs u put under them. silkies r very dependable, excellent moms and very frienly among many other things it is why we love them so much and use them so often. most of my flock is silkies and i'd not trade that for the world even the roos r gental and loveing to their hens as well as they r to all of us(7 people here).
i have hatched as many as 31 silkie eggs under 2 silkies(their doing not mine,lol) to as low as about 8 large fowl eggs to as low as 2 copper black marans eggs under each one cuz they were so huge. so the # of eggs depends on the size they can handle sitting on.
hope that helps,
silkie