Black Sex Links are RIR roo X Barred Rock hen. You have a male chick. Female BSL chicks are solid black.
P.S. When you cross a RIR rooster with a Barred Rock hen you get Black Sex Links which can be sexed by color from hatching (as I stated in the above post). Male BSL chicks look like Barred Rock chicks. As the BSLs mature, the females remain black but get some copper or reddish colored feathers around the neck. BSL males (like yours) become barred as they mature. He will look like a male Barred Rock but likely develop some reddish feathers in the saddle area. I've raised Black Sex Links for years and the hens are egg laying machines. Unfortunately, being hybrids, two BSLs mated will not breed true.