4/1948 late Mandate mail franked w/ Kofer HaYishuv label & accepted at the post

Late Mandate / Kofer HaYishuv mail: 21 AP 1948 commercial cover on "Doar" stationary from TEL AVIV to BNEI BRAK franked 10m per period letter rate using a Kofer HaYishuv label (Ba 133) instead of a Mandate frank, & tied by single strike of the local Mandate postmark - this rare, most such covers date from the interim period & after. Backstamped (unusually, as not a registered letter) 23 AP arrival (Dorf-5, rated B+). Although Kofer HaYishuv stamps were unauthorized for postal use, in the period March-April 1948 these were used for patriotic reasons by senders and generally accepted by the post offices who transmitted those letters onwards - here per postmarks, the franking was accepted untaxed both in TEL AVIV and BNEI BRAK. Very fine strikes; slit open at top.