I would suggest the sling made by Slogan Outdoors called Ultraflex. Try
www.sloganoutdoors.com
I've got their phone number 1-800-383-4454. In my opinion these thermoplastic rubber slings are the best and they last. Check them out for yourself. I've had mine over 10 years now and it's still going strong. I will NOTbuy any other sling.