4D Tactical helmet pad retrofit kits are widely regarded as the best aftermarket helmet padding available. The pads are made of soft memory foam, they make putting your helmet on your head feel like putting a cloud on your head. The outer material is sewn together so it will not tear like glued pads from other manufacturers.
Many other brands of helmet pads are not as soft nor are they as spacious and as a result give the user uncomfortable pressure spots over time. This problem only gets worse as headborne systems become heavier with the addition of night vision goggles, mounts, counterweights, ear protection, ballistic protection, etc.
These pads do stiffen up in the cold, however your body heat will warm these pads up in a matter of minutes and they will offer a mild degree of insulation in cold weather.
The standard Deluxe Combat Liner will fit most helmet systems that do not make use of hard foam inserts, where pads are attached to the helmet shell itself such as Crye, Team Wendy, MTek, etc. The Ops-Core Lux Liner is made specifically for the Lux Liner and has thinner pads to accomodate for the hard foam insert.