Courtesy of Guzz (Nils Stephenson)- originally posted 3 June 2008 but post corrupted on import to new forum. Hi All A couple more stoves to show some variations. As far as I can tell, the Primus 535 was introduced in 1954. It was still being made by Optimus and sold under the Primus name in 1971, but I don't know when they stopped selling it. It is a fully enamelled household stove with two regulated burners with a common tank. An alcohol version is listed in the 1971 catalogue as a 535A, so this variation was available in the Optimus years. There have been some variations in the design during it's life though which I'll try to show. We start with pictures of a stove from 1955. The front of the stove. The back of the stove The top of the stove. Note the shape of the pot stands. The front plate. Note that the name is with raised letters and the company is still AB B.A.Hjorth & Co. The tank cap and logo. The cap is still the style used on other household stoves. The logo is only the Primus name. Now with it's clothes off. The date mark is on the back of the spacing bar for the valve rods. Now we take a look at a stove which must be from after 1960. I have not been able to find a date mark anywhere. The front of the stove. The back of the stove. The top of the stove. Note the new design of the pot stands. The front plate. This time the name is with recessed letters that have been painted white. The company name is now AB Bahco. The tank cap and logo. The tank cap is now with an internal plate to avoid screwing the rubber gasket and the logo has the name in Arabic lettering underneath. Once again with the top off. There's no photo of the spacer bar as there is no date mark. You can see of the previous photo that there is a hook or something in the right hand half. What this is for I have no idea. I don't have one of the Optimus versions, but the main difference from the last one is the control knobs.