The Greifelt may be fitted with a rifle selector lever, but to me this lever looks identical to a safety lever called an Abzugstangensicherung. I had an identical looking lever safety on a Drilling retailed by Louis Knappworst of Braunschweig in 1931. I sold it 9 years ago, so can't go and check it now. I also have a photo of a Sauer and Son Dural action Drilling, of perhaps 1960/70's vintage or thereabouts. Same safety. I believe it is a more comprehensive safety than an 1875 Greener side-safety, however, it was also slower to use for wingshooting of flushed game. Perhaps with more practise and technique I might have got used to it.