"My baby, Stormy, is wild about this! Think of how much cats love paper bags, burrowing and tunneling under things and hiding places. This tunnel satisfies the need for all of that. I have given up on most store bought toys because Stormy prefers the good old stand-byes....paper bags, crumpled up paper, golf balls, and colored straws to play with. So I have become very picky about what I buy for him, as most of it goes by the wayside. Not with this tunnel. He has only had it for 1/2 day, and took to it immediately. He is both playing and sleeping in it already! He seems to love the soft crumply noise it makes, and also the peephole is a huge plus, since he wants to play hide and seek. It's just tooooo cute! I got the yellow/blue, but it's lime green, not yellow. It doesn't make a difference to me but thought it was worth mentioning. The tunnel opening is very appropriate for just about any size cat, about 10 inches in diameter and a decent length. Easy for them to scooch thru. I keep my kitties claws slightly clipped, so this tunnel is not a problem as far as getting torn up. If your cats claws are razor sharp, this product might not last as long."