Spaced armour

When sloped, it reduces the penetrating power of bullets and solid shot, as after penetrating each plate projectiles tend to tumble, deflect, deform, or disintegrate; spaced armour that is not sloped is generally designed to provide protection from explosive projectiles, which detonate before reaching the primary armour.

Impacted projectiles were physically damaged by the 20mm plate, so the main armour could withstand much greater hits.

The skirts thus added 8mm of additional thickness to make up the difference, and could theoretically cause the round to tumble, improving protection against those weapons.

[6] Most of the Cold War spaced armour was designed against medium-to-low caliber kinetic munitions, (e.g. 30mm autocannon and 76mm HESH rounds), especially vehicle side skirts.

Some WWII armoured vehicles used nets of wooden logs at a certain distance from the hull as makeshift spaced armour to protect the vehicle from magnetic mines, thrown shaped charges and grenades, and occasionally suicidal methods (e.g. the Japanese lunge mine).

[5] High-explosive anti-tank-type warheads (HEAT) however use a focused hypervelocity jet of copper or steel to penetrate armour.

To be effective, HEAT warheads must detonate at a specific distance from the target's primary armour to ensure maximum penetration.