Air Post, 1918-34, thirteen unused and six used stamps, unused nos. C3, C4, C7-C9, C10a, C11, C12, C16, C17 (two), C18, C19, used nos. C1-C3, C5-C6, C18, the no. C10a is never hinged, most fine-extremely fine, Scott retail $479.55est.