typical 4 grp / 5 elm Biometar/Xenotar optical design lens
cosmetically not a great condition, but optically no problem
Helicoid is fairly stiff, so I applied high quality machine oil
couple of tiny drops. Now its focusing works very smoothly.

Optics of and samples by the same lens > http://www.oldlens.com/biometar%2035mmf28.html
Biometars > http://spiral-m42.blogspot.ca/2011/12/carl-zeiss-jena-biometar-80mm-f28.html