I have 2 square rulers with the yellow lines- a 12 1/2” & a4 1/2”— I hate the small one- find it very difficult to use ( not sure why) the 12” isn’t so bad, but I definitely prefer the ones with black markings. My creative grid rulers get used the most. At the Grand Rapids quilt show I purchased 2 new SlipFree rulers that are wonderful. I wish I had spent the money to buy the whole set. They also have black markings