1948/49, ½ a. (2), 1 a., 1½ a. and 2½ a., tied by 3 strikes of cds. "EXPERIMENTAL P.O. K-121" (Muharraq post office) to airmail cover to England; one ½ a. slight transportation marks, otherwise fine. The experimentals K121-postmark is the rarest postmark of Bahrain, according to Donaldson just one further cover has been reported.