OVERVIEW:
20mm/85 (20×85 mm) ammunition is designed for use in autocannons and rotary cannons. It delivers effective firepower against light armored vehicles, aircraft, and personnel, with a balance of velocity and ammunition size suitable for specific weapon platforms.

ROLE SUMMARY:
Category: Autocannon Ammunition
Primary Use: Anti-aircraft / Anti-personnel / Light armor
Function: Rapid-fire suppression and penetration
Strong Against: Light armored vehicles, soft-skinned vehicles, low-flying aircraft, infantry
Weak Against: Main battle tanks, heavily armored vehicles, fortified positions
Platform: Autocannons and rotary cannons chambered for 20×85 mm rounds
Integration: Compatible with weapons designed for 20×85 mm cartridges

SOURCE:
Janes Ammunition Handbook
https://en.wikipedia.org/wiki/20_mm_munitions