Our Isbar chicks "look like bantams" next to our monster Marans chicks, but I think they ought to! Isbars are not a heavy or dual-purpose breed, and in general the type for a strictly egg producing breed is much lighter than the heavies/DP. My Isbars lay like champs (daily) and are not frail in my experience. They have been handling the extreme heat (for NW Oregon, I call 108 extreme) and staying fertile. Our pullets start laying right around 16 weeks. LOVE these birds!