Very rare in Alpa mount, portrait lens made by Schacht.
Schacht lenses were mainly made in Exacta mount. This particular
lens type is usually known as TRAVENAR
For Alpa, it is mounted in an EXTENSAN tube.
This lens and the rest of the Schacht family is discussed in
detail in :
Marc James Small, NON-LEITZ LEICA THREAD-MOUNT LENSES, A 39mm
DIVERSITY, published by Rita Wittig and available, signed and
with addenda and corrigenda, from the author for $45 postpaid
in the US. Marc firstname.lastname@example.org FAX: +540/343-7315