The very sketchy included instructions were nearly unintelligible (thank you, China!). Once I decided to completely ignore them, I popped the 4 wheels on in less than 1 minute, velcro’d the carrier to the cart (2 Velcro sleeves, not 3 as stated in the description, but seems snug) and was ready to roll. Rolls and maneuvers very smoothly, plenty of room for my biggest 15# cat. This will make vet visits MUCH easier for me - yay! My only functional criticism is that I wish at least 2 of the wheels locked, preventing the unit from swiveling when placing a cat into/out of the carrier and keeping it from rolling in the car. Not a deal-breaker, though.. Fabric and rubberized mesh seem very sturdy.