Knee protection for both over your pants or in your pants, for example, from Clawgear for their MK.IV pants.
Knee protection for Airsoft is not a must but useful to add to your tactical gear.
You have knee protection that goes over the pants (for example the XPD Kneepads from Invader Gear) or knee protection that can be slid into a separate compartment where the combat pants must be equipped with if you want to use these protectors.
