Was wondering if the xd meprolight tru dot sights are interchangable and will work on all xd pistols. If not what is the difference? All i can find for my xd40 subcompact are ones with the adjustable combat feature. I would like the fixed ones as i dont really want to drop an extra 60 bucks for adjustables. Also would like the orange and green tritium dots. Any info would be greatly appreciated.