I see red through the wing/shoulder area. And if it's the same age as the others, with the red of a comb, definitely a cockerel and not a black sexlink.
That's because most hatcheries use White Rock hens. They are silver base color with dominant white. You can't see white patterning on silver base color. Red sexlinks that use a Delware for the hen frequently look like your boys. Red sexlink hens bred to Rhode Island Red will not produce silver...