Tibet 1930s 1/2t purple Lion Shiny Enamel Cover Lhasa w/Traders Mark

Cover franked with 1/2t reddish-purple, shiny enamel printing, large margins on three sides, surface abrasions, postmarked with partial Lhasa c.d.s., traders mark adjacent in manuscript, some soiling, reduced at one side, nevertheless an uncommon franking