Units can be found in:
East/Russia/Mech. Inf. (Pixel).

For the work of addon, you'll need next files, described below:

rfmi_pixel.pbo
rfmi_pixel.pbo.SLAY.bisign
//This is a main file containing models and textures + signature file.

//Next, you'll need one of config-files, depending on the preferred weapons. This files contains unit classes and their equipment.

rfmi_pixel_bis_wpn.pbo //Default ingame weapons from BIS.
rfmi_pixel_bis_wpn.pbo.SLAY.bisign //Signature file.

//Or...

rfmi_pixel_vil_wpn.pbo //Weapons by Vilas.
rfmi_pixel_vil_wpn.pbo.SLAY.bisign //Signature file.

IMPORTANT!!!

For this addon you need installed ArmA 2:Combined Operations (ArmA 2 with integrated addon Operation Arrowhead).

If you want to use Vilas' weapons versions, you'll need to install Vilas' russian/soviet weapon pack.

Link:
http://www.armaholic.com/page.php?id=9218
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If you want to use replacement, whithout removing any of discribed upper, add one of the files below:

rfmi_pixel_rpl_bis_wpn.pbo
rfmi_pixel_rpl_bis_wpn.pbo.SLAY.bisign
//To replace default units by pixel_camo units, without changing default weapons.


//Or...

rfmi_pixel_rpl_vil_wpn.pbo
rfmi_pixel_rpl_vil_wpn.pbo.SLAY.bisign
//To replace default units by pixel_camo units and replace default weapons by weapons from Vilas.

Moreover, you can use main addon config for bis weapons and replacement file for Vilas weapon in the same time, and vice versa.