Since we had some research take place today concerning the precise cut-off point when AB BAHCO ceased manufacturing and AB Optimus (as Primus Trading AB) took over (seems to be definitively 1964, as the last 6-digit code we found on a no. 1 BAHCO stove is 151064), here are detail photos of the first Optimus-manufactured No. 5 Primus stove, but still using reserve parts acquired by Optimus from BAHCO. The result is an amalgam of Optimus and AB BAHCO, as the photos will make clear. In this very early period box labels still bore the AB BAHCO name, while the tank also carried an AB BAHCO inscription, even though Optimus made the tank. For easy identification, the Optimus/Primus stove is nickel-plated, while the AB BAHCO stove(s) included for comparison are brass. To summarize: this stove features (from AB BAHCO): 1. Burner no. 4138 (standard silent with Primus metal outer cap). 2. BAHCO filler cap (though not the 1963 design, but the earlier one used in 1956 - 8) and airscrew, marked "Primus" on both sides. 3. AB BAHCO top trivet (stamped "Primus"). 4. The box label is the AB BAHCO) one, used from 1956 - 1963 Optimus contributed: 5. Optimus spirit cup (not the broader, shallower AB BAHCO cup, inscribed "Primus"). 6. Optimus manufactured tank, legs and filler (with the air-screw angled towards the right, not at 90 degrees to the tank, as on all previous Primus products from 1882 on). 7. No front stamps or numbering code anywhere 8. No "Made in Sweden" stamp under the tank. Compare this model carefully with the AB BAHCO 1963 and 1964 stoves also included here and the differences are obvious. 9. The Arabic inscription from the second front panel on AB BAHCO products (left from the front panel) is moved to the top of the tank. 10. The AB BAHCO stamp in multiple languages (on the front vertical panel, underneath the airscrew) is absent 11. The legs are of the familiar Optimus profile (not the "stepped" BAHCO leg, with acute angled top) 12. The tank is, nevertheless inscribed (at the top) AB BAHCO, though only on the tank top edge in small script 13. The stamps around the top of the tank are not located in the same place as in later Primus Trading AB stoves, but reversed in location. On later Primus AB models the Arabic "Made in Sweden" stamp is right of the filler assembly, while the Primus logo with stove image is to the left of the filler assembly. Given that the last genuine AB BAHCO model we have found has a 6-digit number ending in 1964, it would seem that 1964 is the real year of transition, but in stages.