These things are awesome! https://www.amazon.com/gp/product/B011KWUPVA/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I recently purchased them because I have been traveling/moving across country and unable to make it to the gym regularly. You can get an awesome workout in just about anywhere. I've been doing a fair amount of research and toning/building muscle is totally possible with these things as well.