| 9. | COST OF SALES |
Cost of sales comprises of purchasing materials, labor costs for personnel employed in production, depreciation of non-current assets used for production purpose, outsourced manufacturing cost, taxes and surcharges, and water and electricity. The following table shows a breakdown of cost of sales for the periods presented for each category:
| Year ended December 31, | |||||||||||||
| 2017 | 2016 | 2015 | |||||||||||
| Changes in inventories of finished goods and work in progress | 227,132 | (302,979 | ) | 64,814 | |||||||||
| Materials consumed in production | 41,057 | 120,847 | 183,831 | ||||||||||
| Purchases of finished goods | 33,877,598 | 36,567,197 | 44,786,912 | ||||||||||
| Labor | 602,196 | 1,313,120 | 787,472 | ||||||||||
| Depreciation | 370,858 | 236,578 | 252,055 | ||||||||||
| Rental | - | - | 23,184 | ||||||||||
| Outsourced manufacturing cost | - | - | - | ||||||||||
| Taxes and surcharges * | 157,314 | 253,039 | 212,516 | ||||||||||
| Water and electricity | 52,796 | 48,557 | 55,522 | ||||||||||
| Inventory provision | 8 | 320 | 342 | ||||||||||
| Others | 120,886 | 238,562 | 197,778 | ||||||||||
| Foreign currency translation difference | (175,493 | ) | 566,691 | (53,152 | ) | ||||||||
| 35,274,352 | 39,041,932 | 46,511,274 | |||||||||||
| * | Tax and surcharges are mainly Urban Maintenance and Construction Tax (7% of Valued Added Tax payment amount), Extra Charges of Education Fund (3% of Valued Added Tax payment amount) and Local Surcharge for Education Fund (2% of Valued Added Tax payment amount). |