You can substitute about 400 meters of any sock yarn.

Sizes are for foot circumference of  8", 8.75" and 9.5"

There is an error in the marker placement at the beginning of the heel. This correction, using only TWO makers, was provided by designer during a CAL…

“GUSSET SECTION: Place markers: Fold sock in half and locate center stitch on top of foot. Place markers in 9th(10th,11th) stitch on either side of center top foot stitch. Markers should be located about 1 stitch in from the side edges when the sock is folded flat.”

From the CrochetMe website:

"I like crocheting socks from the toe-up. You can try them on as you go and adjust the calf length to the amount of yarn remaining. I also like to crochet the heel as I go; no after-thoughts for me. The custom fit is better and you’re finished when the cuff is done. I designed this pattern so I could crochet socks my way – toe up in one piece with a gusseted heel."

Also from the CrochetMe website:
“Upon closer reading of the pattern as posted, I’ve realized the source of the confusion on the heel placement. When placing the markers for the gusset round, only place a beginning marker and a side marker. Do NOT place a marker in the center top of foot. The “midpoint” marker refered to in Gusset Round 10 is the SIDE marker. This extra marker may also explain why some crocheter’s socks were coming out huge. If you were increasing at each of 3 markers (instead of 2) each round, your stitch count would be way off and obviously the sock would be way larger than intended. Dorothy”