Seals are disposable which aims to prevent the open by unauthorized persons. And once correctly locked, it can not open unless by violent broken (i.e. cutting).
Once broken, it is unable to use again so as to prevent the theft, leakage, broken or change of goods or information. So it is one time use.
Of course, the cost of seals also depends on the material. The cost of plastic is much cheaper than of steel. For large goods, by plastic material is easy to operate. While cable seals of steel material is usually used at cabinet, which is stronger.
