The invention is a chain unit comprising first and second link units, a unitary outer plate, and first and second pins. Each link unit comprises two inner plates with two rollers positioned therebetween. The outer plate straddles and is secured to the link units. Outer plate comprises two walls and a bridge positioned therebetween that spans the tooth engaging space between link units. The unitary construction of the outer plate provides a structural integrity that prevents the plates from separating when the chain is exposed to force. A plurality of chain units can be linked together to form a chain.