Paper shells can be used to load various items, and the specific size depends on the size and weight of the loaded items. The following are some common uses and corresponding size ranges:

1. Food packaging box: Paper shells are generally used to package food, such as cakes, biscuits and chocolates. Its size varies according to the size and shape of food, and it is usually relatively small.

2. Express packaging box: Paper shell is also widely used in express delivery industry, which is used to package all kinds of logistics and transportation goods. Its size will vary according to different goods and transportation needs, from small to large.

3. Home improvement furniture packaging box: paper shells may also be used to package furniture, electrical appliances and other large items. This kind of paper shell is generally large and can be used to package and protect large items.

In a word, the size of the paper shell depends on the size of the loaded items and the packaging requirements. It is impossible to give a specific size range, because different items and different industries have different requirements.