Candle wicks - Square braidOriginally, square braid candle wicks are meant to be used with beeswax candles, but they're used as well with large pillar and container candles and with 'novelties' candles.
Thicker than their flat braid equivalent, square braid wicks allow for pillar and container candles with a diameter larger than 125mm (5 inches).
The classification system adopted by Candlewic goes from 6/0 to 1/0, where 6/0 is the thinnest and 1/0 is the thickest then continues with other figures, namely from #1 to #10, where #10 is the thickest (rope, really, used for large outdoor terracotta mosquito candles).
The difference between the two figures is that, if the first is braided in a classical way, the second is "loosely" braided, which makes the wick larger without making it heavier. Also to be noted, the second classification uses the smallest number (#1) for the smallest wick; in the first classification, the smallest number (1/0) indicates the largest wick.
Just like a flat braid wick, the square one curls slightly as it burns, allowing for a better disposal of the already consumed part of the wick and minimum carbon buildup.
It is possible that your wick salespoint doesn't use the number of ply to identify square braid wicks but rather indicates the size and type of candles they are most appropriate for.