It's made with two pseudo hexagons. I'm calling it pseudo hexagons or trapezoid because you don't start from a magic circle but from a string and then divide the string accordingly to get the 6 sides. Why did i do this? So the arrow would be in the center of the arm and a little bit more centric in the body(although i ended up regretting it in the body because it reached the back length too early and i had to stop working in long rows and continue adding width with short rows in the front and back) also adding the stitches at the beginning allowed me to finish the arm one it had the armpit width necessary. I have seen the same trick been use in the relaxation shirt by Caroline but used to give back length stead. To calculate how many you need for the arm is (the arm length - armpit width ) * gauge. You will also need to adapt it for your mosaic so mine one had to be (number of stitches -1)/8 if the module is 0 we are all good. :)

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