DK

DK Means Double Knitting and refers to the weight you get by holding two Fingering Weight yarns together and working them as one yarn.
DK Weight yarns knit at about 5.5 stitches per inch (22 stitches in 4 inches / 10cm).
Crochet gauge is about 14-15 single crochets (sc) in 4inches / 10cm.
In the number system, DK is a #3 Light