(To upgrade to this model you have to cut/wear out the sides inner top shell of the Ender 7 in order to fit the new height/volume added with the 5015 fans to fit properly witout hiting anything while printing (shown in photos what need to be wear out, I used a Dremel to do it))
The fans can be fixed with only 1 screw/nut each, it will hold them well enough in case that you cant allign the fans with the air hole and the 2 screw fixing holes.