Leg
Using MC, CO 64[68] sts. Divide sts between 4 needles, placing 16[17] sts on each needle. Join to begin working in the round, being careful not to twist. After first round, place safety pin or split ring marker in work to indicate beginning of round.

Work in 1x1 Rib until work measures 2 inches.

Work in stockinette st until work measures 3 inches.

Join CC and work Rounds 1-3 of Chart A.

K 3 rounds using MC only.

Work Rounds 1-15 of Chart B1[B2].

K 3 rounds using MC only.

Work Rounds 1-5 of Chart C. Break CC.

Continue in stockinette st until work measures 7.5 inches.

Heel Flap
Instead of using a new needle to begin next round, work all sts from first needle onto last needle of previous round. There will be 32[34] sts on this needle; the Heel Flap will be worked back and forth over these sts. Turn work so WS is facing.

Row 1 [WS]: [Sl 1, p1] to end.
Row 2 [RS]: [Sl 1, k1] to end.
Repeat these 2 rows 19 times more, then work Row 1 once more.

Turn Heel
Row 1 [RS]: K18[19], ssk, k1. Turn work.
Row 2 [WS]: Sl 1, p5, p2tog, p1. Turn work.
Row 3 [RS]: Sl 1, k6, ssk, k1. Turn work.
Row 4 [WS]: Sl 1, p7, p2tog, p1. Turn work.
Row 5 [RS]: Sl 1, k8, ssk, k1. Turn work.
Row 6 [WS]: Sl 1, p9, p2tog, p1. Turn work.
Row 7 [RS]: Sl 1, k10, ssk, k1. Turn work.
Row 8 [WS]: Sl 1, p11, p2tog, p1. Turn work.
Row 9 [RS]: Sl 1, k12, ssk, k1. Turn work.
Row 10 [WS]: Sl 1, p13, p2tog, p1. Turn work.
Row 11 [RS]: Sl 1, k14, ssk, k1. Turn work.
Row 12 [WS]: Sl 1, p15, p2tog, p1. Turn work.

Narrow Size Only:
Row 13 [RS]: Sl 1, k16, ssk. Turn work.
Row 14 [WS]: Sl 1, p16, p2tog. Turn work. 18 sts remain on this needle.

Medium Size Only:
Row 13 [RS]: Sl 1, k16, ssk, k1. Turn work.
Row 14 [WS]: Sl 1, p17, p2tog, p1. Turn work. 20 sts remain on this needle.

Both Sizes:
Sl 1, k all sts; using the same needle, pick up and k 22 sts along edge of heel flap and in the space between the heel flap and the top of the foot. This will be designated Needle 1.

K the sts on the top of the foot onto the next 2 needles; these will be designated Needle 2 and Needle 3.

Using a fourth needle, pick up and k 22 sts along the remaining edge of the heel flap and in the space between the heel flap and the top of the foot, then k the first 9[10] sts of Needle 1. This will be designated Needle 4; end of round is now situated between Needle 4 and Needle 1. Move safety pin/stitch marker accordingly. 94[98] sts.

Gusset
Round 1: K all sts.
Round 2: K to last 3 sts on Needle 1, k2tog, k1; k all sts on Needle 2 and Needle 3; k1, ssk, k to end of Needle 4. 2 sts decreased.
Repeat these 2 rounds 16[14] times more. 60[68] sts.

Narrow Size Only:
Move first st of Needle 2 to Needle 1. Move last st of Needle 3 to Needle 4. 15 sts on each needle.

Medium Size Only:
17 sts on each needle.

Both Sizes:
Work in stockinette st until foot measures 7.5[7] inches from back of heel, or 2[2.5] inches less than desired length to end of toe.

Toe
Round 1: K to last 3 sts of Needle 1, k2tog, k1; k1, ssk, k to end of Needle 2; k to last 3 sts of Needle 3, k2tog, k1; k1, ssk, k to end of Needle 4. 4 sts decreased.
Round 2: K all sts.
Repeat these 2 rounds 10[12] times more. 16 sts remain.

K to end of Needle 1. Break yarn, leaving a 12-inch tail.