"Spezialhaus" is just too iridescent and imprecise a word. It could mean a specialized walk-in-shop, or - and maybe rather - a specialized mail order business. The house Hernalser Hauptstraße No. 62 still exists in Vienna; its street situation is not where you would expect a shop with busy individual customer traffic.
The Bratislava firm at the time still was conducted under the old and respectable name "Josef Seifert", with the addition of Karl Seifert as owner. So, a connection is certainly not impossible. After all, Karl Seifert had already before 1918 dabbled in another field, namely in passementerie.
- Yes, a beautiful and today extinct word, look it up in Googgle. :-) -
He had shared stationery with Franz Kühmayer, factory of passementeries en gros in Pozsony/Pressburg. That was one of the big players in a field which frequently was still dominated by the old "Verlagswesen" with their many house workers who delivered their home-made goods to the so-called "Fabrikant". But Kühmayer had a big modern mechanical factory and many factory workers with regular working hours. Now, World War I, the Great War, was the opposite of colourful military uniforms with passementeries, and court uniforms were no longer in new demand either, in fact demand must have completely broken down. So, for some reason, Seifert and Kühmayer decided for some kind of joint venture and shared their envelopes. See here this very interesting philatelic thread:
https://www.altpostgeschichte.de/index.php?thread/2985-tschechoslowakei-ausland/It seems quite possible to me that one or two decades later, under the impression of the world economic crisis, Karl Seifert might have tried to dabble in still another field, and to establish a mail order business in photographic apparatuses in Vienna, which after all was only 55 kms away. He had, as I mentioned, already before been a dealer in sporting goods and equipment, as well as in gentlemen's clothing (leisure as well as ballroom). Maybe he was able to acquire cheaply some stocks of photo stuff from a now bankrupt firm, and hoped to become able to pander it advantageously via mail order... a lot of speculation, as I admit.
