The offer does not provide important constraints or out too little. The missing information is provided on the website of the seller company available. The link to it is not in the text of the offer. It is obtained with the product, which accompanied the information in writing. That's what I first experienced when I find this page, I would like to know before buying. I would probably be better to look for it.
The stretching rod alone is to be used only in the door frame of solid materials (metal, hardwood) and with non-slip surface according to instructions. Even then, the maximum load capacity is already limited to 150 kg. Otherwise are glued to the door frame brackets increase the skid resistance and increase the resilience bolted brackets.
Experience with this bar on my built softwood old door frames:
Softwood is considered elastic and soft. Such doorway are unsuitable for this bar to instructions. That is why it is particularly on the right place. The remaining panels of the door frame (frames - only boards) are not easy to distinguish from the floor frame! But most of these relatively narrow, but compact floor frame (the door leaf) surrounding the closed door immediately, is possibly stable enough.
On most doorway of my old apartment it cracks when tightening the rod enormous, the lacquer tears at the joints, mortar dust trickles (more because I have not dared).
On one of the six doorframe but enough gentle tightening without glue or screws to hold a 90-kg man, quietly hanging on the rod. Vigorous movements I dare not there.
I use the rod for hanging exercises to regular stretching on the forearms at tennis or golf elbow problems.