E1-grade MDF at 0.6 in thick is the structural spec that matters here - thin board flexes underfoot and unsettles a climbing cat, while this holds firm across a 37 x 15 in footprint. Natural sisal rope of 0.2 in diameter wraps the posts, over paper tubes of the same thickness, giving claws something with grain to pull against. A ladder links the levels for cats that climb rather than jump. Soft plush covers the perches and condo. Height reaches 56 in on a 15 x 20 in baseboard and the tree weighs 23 lbs.