Perfect for a litter of kittens or puppies. Assembly is literally a snap. You can put it together quickly and it holds together firmly - for kittens. As for puppies, because it so light weight, you could still use it but you would have to reinforce it with the zip ties (that are provided) and secure the entire pen to the floor by attaching more zip ties to something heavy (little sand bags, or weight plates from a dumbell/barbell. Its ease of assembly was a particularly great feature in my case. My mother-cat wasn't happy with the pen's initial placement and kept removing the kittens from it (via an ottoman left beside the pen to ensure she could always get in to nurse them) to hide them underneath a bookcase. I simply took down the pen and reassembled it AROUND the bookcase. She's been happy ever since. I use the pen in conjunction with underpads used for incontinent bed-ridden patients. About 4 to 6 will cover the floor depending on how large a pen you want. Until the kittens figure out how to use their litter boxes I simply replace the soiled underpads as needed.