This is a Kosmo format attenuverters module. Not much to say beyond that! There are three attenuverters. One has a switch to select 10 V input instead of the input jack. There are jacks for output of the sum and inverted sum of the three channels. Response to slider position is nonlinear, giving you finer control near the middle for setting small values.
Schematics, KiCad design files, Gerbers, docs here: