Thailand Post issues cards with postage prepaid on the reverse, in this case a 6-baht imprint almost the same as the front of the card.  So it’s not quite a maximum card.  This Mae Sot Customs Boundary Post is “Thailand’s Western Most District” and is at Rim Moei Market, Amphoe Mae Sot, Tak.  Instructions for use in Thai and English.  Unused.  Grade: 1