This framework consists - A fixed part around (outer rectangle), which theoretically can not be changed and that allows (easily) to set this framework on the frame of the cabinet where the unit is recessed, - And a portion (the inner rectangle) composed of lamellae which can easily remove one by one with a small hacksaw blade. As for me, no problem to adjust the height of the opening, removing 6 of 7 horizontal slats up and down, I cleared 30.6 cm high when my microwave is 30, 3 cm By cons by removing all the vertical slats on the right and left, I emerges as 53.2 cm wide while my microwave able 54.7, so I can not position it properly in this framework, I will have to cut the electric hacksaw the uprights supposed to remain fixed, it will break this framework to remove 0.75 cm on each side. Too bad, especially since no other manufacturer offers no framework adapted to the dimensions of my oven. So I do recommend purchasing this context that if your oven dimensions are strictly between 23.3 cm and 31.8 cm high and 44.8 cm wide and 53.1, which is absolutely not specified in the description, which I consider as abnormal because we do not buy knowingly.