400w Poltava DNaT 400-4

Nice old Soviet 400w SON-T lamp made by Poltava in the former Ukrainian SSR.
Quite interesting in that it has what appears to be a GE Lucalox style external amalgam reservoir.
The arc tube is far less translucent than western lamps too.

The quality of the outer glass, like the other Soviet lamps I have seems pretty poor tbh, full of visible and tactile imperfections!