Shower room Soviet door nameplate vintage - Old Russian public washing room door sign plaque

Apparently, this sign is from the shower room of some Soviet enterprise.
The sign says the word "shower" with Russian letters "KPK".

Made of aluminum.
Size is 17 x 10 cm.
Weight is 120-130 g.

I have not found that these three letters denote specifically in use on this plate.
Since in general the abbreviation of these three letters has many meanings.

Big. Cool. Original.