Hey guys. Looking to get a Glock 19 Gen 4 from my LE dealer and here is his price list. Question is, what is the difference between fixed, adjustable, steel, NS, and trijicon? Obviously different sights, but is steel referring to the slide? Look like great prices, don't they? What's the difference between NS and trijicon? I'm assuming NS stands for night sight, but isn't trijicon also a night sight?