Somebody already posted it, but it's a Pilates ring, and I absolutely hate it. 

The poor folks at Nintendo probably don't know any better, since Japan is not big on gyms, but "exercise" like this and Wii Fit misinform and mislead. 

The goal of exercise is to lose fat and build muscle. BBB Routines (Bosu Balls, Bands, and Baby/Body Weights) are bad at both. Fat loss is done in the kitchen, not the gym. You can't out exercise a bad diet. The point of exercising, on a diet, is to preserve any muscle that you have, while you are on a calorie deficit (Your body wants to lose muscle when you are not getting enough food.) The more muscle you have the higher your metabolism is. Having more muscle prevents yo-yo dieting, where you just gain back all the weight you lost when you come off your diet. In order to build or keep muscle you need to lift heavy enough that you can only do four to ten reps per set. BBB Routines are the exact opposite of that. They are also very popular with women, because many women are afraid of getting bulky (they can't because they lack the testosterone required). 

"But Cerebral, I know this one fitness guru who does bodyweight exercises and is in great shape!"

Yeah, that's because...

1. He got in that shape by lifting heavy weights on a real training program, and is now just maintaining. 

2. And/Or he is on steroids. 

3. He is genetically gifted, and predisposed to putting on muscle easily. 

Now, don't get me wrong here. There are good bodyweight exercises that can be fit into a proper routine. Dips, and Pullups for example work well. But that is because with both of these exercises you are moving your entire body vertically. When you do pullups you are lifting 100% of your bodyweight. When you do dips you are lifting 100% of your bodyweight. The same cannot be said for pushups, situps, crunches, planks, or barless squats. 

Japan might not know much about gyms but they know how to stay slim.