The children’s Trestles 30 is a well designed package: it’s warm enough for three season use and boasts an extra zipper opposite the main one, allowing the user to put their arms out without exiting the bag.
Unlike adults’ bags, children’s bags do not have a temperature rating standard. Marmot rates this bag at -1°C.
The one liter bottle seen in one of the product images is not included - it’s there just to give a scale to the packing size.