Seven layers set at 11.5, 21.5, 37.5, 42, 54 and 71 in give this tower a measured climb rather than evenly stacked shelves - the spacing widens toward the top where confident cats jump and stays close at the bottom for the timid ones. The condo has two entrances, 7 in across, and measures 15 x 14 x 12 in. Each layer holds 33 lbs. Engineering board and sisal rope over a 24-in square base bring the weight to 57 lbs, which is what keeps a 71-in frame from swaying.