Hi, there has been a recent post of a Swedish Primus No.71 stove, which also has the German CTR marking. In this case CTR 8. https://classiccampstoves.com/threads/primus-71-c-t-r-8-for-the-german-market-nos.35233/ The CTR designation refers to the German Imperial Institute of Chemistry and Technology, and the Technical authority for setting Standards. This Institute was founded in the late 19th/early 20th Century and became the Technical Authority for Germany. The idea was subsequently copied by the British and the National Physical Laboratory was founded. I guess just as we in the UK have the BS (British Standard) designation the Germans might have had a CTR system. The CRT Standards System seems to have existed until the end of WW2, and the partition of Germany, when it was replaced by two separate Standards Systems. There are now at least 4 different stoves shown on CCS, which exhibit the CTR mark. 1. The recent Primus No.71, dated 1941, which is marked CTR 8: https://classiccampstoves.com/threads/primus-71-c-t-r-8-for-the-german-market-nos.35233/ 2. A Juwel No.33, also from 1941, marked CTR 5: https://classiccampstoves.com/threads/juwel-33-1941.18074/ 3. An Optimus No.8, also probably from the WW2 period, marked CTR 10: https://classiccampstoves.com/threads/optimus-no-8-german.20458/#post-210280 4. Another Juwel No.33, marked CTR 5: https://classiccampstoves.com/threads/juwel-33u-brass-tank.22239/ There is also another Juwel No.33 from the WW2 period with a 4 bar Eagle and Swastika marking, which Christer suggests might refer to an alternative Standards Authority (perhaps operating alongside the CTR System?): https://classiccampstoves.com/threads/juwel-33-4-bar-eagle-swastika.23462/ The CTR System, and how it relates to stoves, is a subject worthy of additional research. Unfortunately I am not a German speaker, so Google searches are of limited use to me. We need volunteers. If the CTR Standards system operated as others, it would seem logical that each device would have a type approval, and that number would appear on the relevant device or object. I have only illustrated a few stoves in this post, but we have three types of small gasoline fuelled stoves with three different CTR numbers: CTR 5 for the Juwel No.33 CTR 8 for the Primus No.71 and CTR 10 for the Optimus No.8. Just some thoughts Best Regards, Kerophile.