Since this is a made to measure pattern it can be made with any yarn weight/hook you have available and adapted to any size you need.
I made my sample with La Abuelita from hilos omega and a 4 mm hook, but I am a tight crocheted and it curled a bit, so I would do it more loosely or use a larger hook next time, I decided to make it for my dog, but it can be easily adapted to be made to any size.