The Sock Ruler ?is constructed of a heavy duty, yet flexible plastic; an innovative measuring tool for sock knitters that goes inside of the sock, allowing it to lie flat and ensure accurate measurements (both metric and imperial). A very nifty tool to have for accurately measuring socks, mittens or hats. The Sock Ruler® will measure (CUFF DOWN): Length of cuff Distance from top of cuff to start of heel flap Distance from finished heel to start of decrease for toe The Sock Ruler® will measure (TOE UP): Distance from toe to start of heel Distance from finished heel to start of cuff Length of cuff Sizings The Sock RulerAdult: is for adult sized feet and children size largeThe Sock Ruler Junior: is a set of two, one for babies and one for infantsThe Sock Ruler Combination: includes all three Sock Rulers!