This door gym is a great concept. Unfortunately cause its mass produced, i had to redrill the last hole for the bolts to hold it together, i thought it was me, but no. Hopefully, the bar that hooks over the top of the door frame and takes all the weight will sit flat, eventually. I see why they've included the metal hooks, to take the stress off the top of weak door frames. But these hooks are really too small to hold the weight of anyone, mainly cause they've got four holes each with tiny screws and tiny raw plugs. Also, would you really want to drill into the door lintel? Potentially reducing the strength of it, which you are hanging off?
Type of thing to see before you buy, even if you pay more for it. But then for £20, can you complain?