they use a couple of different threads but they usually fit the brushes you have. They use sizes appropriate for brush size so you get more bite with the larger brushed but I'm sure everyone just about uses the same standards. I got that same kit as a gift, loved it. Really nice that all the pieces are brass so they are more gentle on the gun. You can def use either kind of patch. I actually prefer the square ones. They're cheaper and I always screw up the size enough to get it stuck. BTW, if you do get something stuck, just twist off the cable, pull it out, and send a cleaning rod down to back out whatever you get stuck. (Or in a pinch a chopped up coathanger piece.
That is an expensive kit though. If you have most of the other pieces I would suggest just getting the cheapest rifle kit. Otis makes good stuff, they knew that people know that, they charge accordingly. Not saying its a ripoff, just that they aren't lowballing much.
