Gym rings are an essential in every strength & conditioning facility. If any place doesnt have this tool, they are not meant for strength and conditioning! Gymnastic rings allow you to work on shoulder stability and strength, allows you to perform all the gymnastic movements which work your core to the max. Huge repertoire of exercises to be performed and all are beneficial no matter who you are!
Invest in a set and I promise you that you will not regret. Best part is they are portable as well so you can bring them around with you.
Picture by Galileo at Blah Blah BlahG!.