I ordered this sling to replace the one they issued me in the hospital. That one was killing my neck and I just wouldn’t wear it as often as I should have. Read my post on Shoulder Pain if that is why you’re considering a sling.
Anyway, I bought this sling and it is very comfortable. It includes a removable Velcro-attached “pillow” that goes between the sling and your body so that your arm will be held in the proper position. There is also a strap attached to the pillow that wraps around your body to keep your arm close to the body. A neat feature is a rubber squeeze ball positioned right where your hand exits the sling with Velcro. It’s removable too. The idea is that you will exercise your hand by squeezing the ball, keeping your muscles working and your blood flowing. This helps reduce swelling and wakes up your sleeping hand. This sling is infinitely adjustable for either right or left arms and bodies of all sizes.
Bilt-Rite Mastex Health Shoulder Immobilizer, Black $38.34: http://amzn.to/2sNuAQE