Shortcoming:
If it goes up the stairs but down or "out of the trunk," the belt from the chest towards the rump and hind legs slips are highly gelupft. Thus, the belt is unsuitable for this purpose.
Conclusion:
For dog in the trunk or stairway to support high I would buy it again.
In all movements to assist the dog down I do not find it helpful. (I have my dog braked with hand on chest).