In 1996 the Nona family was reinforced by one more 120-mm automated self-propelled gun 2S31 "Vena".

This artillery piece is an armoured amphibious vehicle on BMP-3 track chassis.

It is equipped with:

• Automated elevation and traverse guidance system with a fire setting computer;
• Automatic survey and orientation system;
• Day and night optronic recon-naissance and designation system for high accuracy firing.

The SPG exhibits the destructive power of high-explosive projectile at the target compared with the effect of 152-155-mm high-explosive projectiles.

SPG can fire with all types of native and foreign 120-mm mortar shells.