Posterior deltoids compound exercise?

Hi for the rear shoulder you dont need heavy weight, try this get a bench position it at 45 degrees and hug it with your arms dangling down and with 5 to 10 kg weights, now lift weights to the side without removing your chest of the bench. Alternatively you could do this without the bench bend forward to 90 degrees dumbells in-front of you lift to the side and back in-front whilst staying at 90 degrees.