There were a few question about Claus' 1381 so I thought I'd post mine. It's got all the bells and whistles that could be ordered extra, so might be a good example. It is a 1381 from 1944 (AI 3) and has the optional level gauge as well as the optional pressure gauge. It is still configured for alcohol. So far I havn't tried it. The second last picture shows the air restrictor which is just a flat strip of metal across the air opening to the jet.