Transvaal 1909 CSAR Perfins on OHMS Railway Letter, Rare

1909 OHMS Envelope franked block of four (1 defective) KEVII ½d's WITH OFFICIAL "CSAR" PERFINS, The letter from Germiston Station (cds's 30 APR) to Germiston town with delivery backstamp. Fold at left, rare on cover, especially as a seemingly proper commercial use for a 1oz letter. One of only a handful of CSAR franked letters extant. The stencil-cut and needle-perfined stamps were considered unsuccessful and replaced by CSAR overprinted stocks. See additional image.