They come in several types. * Grey, basic items that typically have no attribute modifications. * Green, drops off most mobs or rewards for missions. Will have set stats. * Crafted green will sometimes have 1 mod slot you can expand. * Blue, better than green of same level and will have set stats, sometimes with mods available. * Orange, are better than blue, green, or grey and will have 4 open mod slots. They are very customisable and can be modified through every level so you keep the same armor throughout leveling. * Purple will have set stats but will have better states at that level. Creating a custom toon to stay at level 15 and never level will prefer purple but orange is better if you want to keep leveling.