Very economical and efficient! And yes, it's a cardboard carrier, but don't think it's flimsy in the least! This one is made from extremely durable DOUBLE-WALL corrugate, and it's wax coated so you can just wipe away wetness from accidents.
How tough is it? We've carried 20-lb. cats with ease! (Cats that have broken the bottoms out of cheaper-made cardboard carriers!)
Collapsible for easy storage.
About 18" L x 9½" W x 11½" H.