Had this for almost three years now and it's still in good shape. It comes with a cup for each side which you can fix to the doorframe, and these cups hold the bar up. Don't try to use the bar without the cups thinking a friction fit will work, just look at some videos on YouTube if you want to see what happens!
This review is also available on Amazon: https://www.amazon.co.uk/review/R1G0J76R602GTP/ref=cm_cr_rdp_perm