special invoice. The outdoor box switch station is mainly composed of SF6 or vacuum fully insulated compact switch cabinet or other switch cabinets such as KYN28A and metal insulated houses, which occupies a small area and is easy to move. Outdoor box-type switchyard is a semi-public facility. Although ordinary invoices and electronic invoices are also acceptable, the input of special invoices can be deducted from tax. Outdoor box switch station belongs to the category of "low voltage switch, protection control device" in tax classification.