BACK
Using 3.25mm needles and yarn A, cast on 113 (125:137:149:163:173) sts.
Row 1 (RS): K1, *P1, K1; rep from * to end.
Row 2: *P1, K1; rep from * to last st, P1.
These 2 rows set rib.
Cont in rib as set for 6 (6:6:7:7:7) cm, ending with WS facing for next row.
Next row: Rib to end, inc 1 st at end of row.
114 (126:138:150:164:174) sts.
Change to 4mm needles.
Row 1 (RS): Using yarn B, knit.
Row 2: Using yarn B, knit.
Row 3: Using yarn B, K2 (2:2:2:3:2), *Sl 2, K4, rep from * to last 4 (4:4:4:5:4) sts, Sl 2, K2 (2:2:2:3:2).