This is the most ridiculous gadget ever and totally disregards common sense. Its a health risk!
If someone's worried about being overweight you are looking at heavy bags of around 40 pounds. How on earth are you meant to lift that weight off the ground keeping the scale horizontal. And that to for a few seconds. I feel my back is going to break. Because the strap is so flimsy and slim, it offers no support so here you are lifting a 40 lbs suitcase (not a duffel bag) which is swaying as it is being held up by one tiny strap so all the weight falls on one point. Unless the swinging stops, the machine cannot take a reading.
 Its like no thought was put into its design and the laws of physics are being challenged here.

Edit: I am returning this to amazon but if I wasn't I would smash it violently, as it is so awful and now my lower back hurts.  its just not worth damaging your back. if you have to use a bathroom scale, then do that.
Please note that most of the positive reviews come from those who were sent this product to review. Friends of the owner? And some from people who haven't even tried it! So read the reviews carefully, with a pinch of salt and don't go by the rating. I did and it was a mistake. I should have tried one of the others available. Now its too late as i am travelling today. Yes, I am using the bathroom scale which is not bad and gives a consistent reading each time. Just make sure your's is accurate.

Also if you go on youtube and see the official video, you will notice that a duffle bag is being used in the demo. And that too by a tall, built guy. The owner of the company.
To understand the ridiculousness of the design, before buying this, take a doubled up piece of thread and hang a tote or bag full of groceries on it. Consider two things: 1) does the bag EVER stop swinging? 2) how hard is it to hold  the bag up by such a thin support ? 3) does the amount of pressure on the thread ( and weight on your hand) vary depending on which part of the strap the thread rests upon?
I think this will give you an idea of how bad the design is and the issues you will face with this gadget.
At best you can use this to weigh your evening bag.

It makes me really angry that such a daft device is being promoted in ways I don't think are 100% genuine. Sorry to say.