Yeah, you need to get the welded-seam elbow from the liner maker. That way, you don't have the worry of the cheap elbow possibly coming apart. This is a 15* but it's kinda hard to see how much it turns, from the angle of this pic. It doesn't turn a whole lot...
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AH i think I might need a 30 degree for mine, but yeah it's not that hard to change cause I am still in the process of fabing up my 2 piece block off plate.