>>76807594 (OP)
An adjustable kettlebell or dumbbell can be used for muscles all over your body and takes up less space than this thing. Every alternative to weights, even when useful, are still much harder to get use out of. Weights work for everything. Even just walking around with a weight in your hand is useful.
If you don't want to spend a lot of money outright then search Amazon for 1-inch dumbbell handles and 1-inch weight plates. You put a plate on the handle like a barbell and screw it on. You can stack all of these pieces on top of each other in less space than this thing, and it's useful for everything, can you can upgrade your 1-inch kit piecemeal as you get more into it.
Space 'saved' on a gimmick is space wasted. Likewise money and time. Stop falling for this shit. You're only sabotaging yourself: once you have the gimmick and realize it sucks, you'll go back to not working out, relieved that the impulse to improve yourself has faded away.
Here: position one arm to do a bicep curl with an invisible weight, make a fist, then do a curl with your other arm pressing against the movement. Dynamically adjust resistance to keep the movement hard across the full ROM of the curl. You can train arms better than this thing offers, with no money or space spent at all. You can do the rest with pushups. Pushups too easy? Keep one arm planted under you in the normal pushup position, while pushing the other arm away from you. You're now training the arm under you much harder than the far-flung arm. You can progress to a one-armed pushup with these.
