Foil sensory blankets, this is one of my personal favorites at the moment.
These have multi purposes which create some amazing sensory experiences for children. The children can explore the wonderful crinkly noise which it provides as well as the reflective light, which helps explore touch and sound combined. The blankets also create a lovely calm effect, I have used these sensory blankets multiple times at the end of a sensory circuit where the children can choose to lie under them or wrap themselves up in them to create that calm.