Blue Dart Express — adjustable posture corrector

Address:

Mumbai City, Maharashtra, 400053

Wrong product/unable to use product due to lack of appropriate instructions
Since it's a posture corrector, there should be some mechanism to hold it against the back or to pull the back such that on slouching, the posture is corrected
However, there appears to be no mechanism to strap on the device to the back
No instruction manual was provided either