I had the same question and they said that three sixtels will not fit..... Even though they are only 1/4 wider than a pin lock.
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Primary1: Pliny the Elder Clone
Secondary1: Blueberry Wheat
Secondary2: Cherry Wheat
Keg1: Blue moonish Clone
Keg2: EdWort's Kolsch
Keg3: Bell's Two-Hearted Ale Clone
Bottled: Pumkin Ale, DFH 60min, Choc Stout, Choc/Coffee Stout, Apricot Ale, Banna Foster Cream Ale, Christmas Ale.