My daughter was interested in thin book since she was 2 months, she is 4 months and still enjoying playing. Attached teether works wonders as well. Little mirror inside is her favourite, squiky page as well. All book have lots of textures and beautiful colours. What to not love. Only down side, it's can't be washed in washing machine, I did and it have condensation on handle now. Hope mold not going to grow.