Gymnastics straps are simple and highly effective pieces of gymnastics equipment everyone should have in their gym bag.
Here is a video showing you just how versatile these things are.
Here is Chinese gymnast Wangtang6911 using a similar technique (arms through rings straps) to train his ring strength elements and transitions like Iron Cross Pull to Maltese.
Once you get stronger you can start adding weights. That will give you a very fine control over your strength progress.
Wangtang with a 7 kg weight belt.