This Wraps Per Inch Tool is perfect for spinners or knitters who enjoy substituting yarns. Wrap your yarn around the 1" indented ruler in the center so that the yarn neither overlaps nor has space between the wraps. The number of wraps per inch will tell you whether you have fingering weight yarn, worsted, bulky, etc. Plus, the keychain attachment lets you carry it with you, attach it to your knitting bag, or easily hang it on the wall near where you work!