In Kushy
Ch4, sl st to first ch to form a ring.
Round 1: Ch2 (counts as a htr), 11htr into the ring. Sl st into the second ch. (12 sts)
Round 2: Ch2 (counts as a htr). (2htr, htr) around, into the third loop of the htr in the previous round (this is the loop underneath the 2 loops at the top of the st). You will finish on 2htr into the last st. Sl st into the second ch. (18 sts)
Round 3: Ch2 (counts as a htr). (2htr, htr) around, into the third loop of the htr. You will finish on 2htr into the last st. Sl st into the second ch. (27 sts)
Round 4: Ch2 (counts as a htr). Htr into each st around, into the third loop of the htr in the previous round. Sl st into the second ch. (27 sts)
Fasten off. Use this tail end to join to the next free stitch on your second tree rings slice (this is next (to the left of) to the last sl st of row 45. You can do this in whatever way you wish, but I did around 4-5 whip stitches in the same spot. To give more stability, also do 4-5 whip stitches in the next free st along. Weave in both ends of your tree rings slice.
In Rustier
Row 46 (RS): 2htr into the first st of row 45. Htr into each st across, finishing with 1htr into the last dc of row 45 (this is the dc that was made into the tree rings slice). Sl st into the third loop of the second, third and fourth htr of the tree rings slice. Turn. (108 sts - 3 sl st do not count as sts)
Row 47 (WS): Dtr into each st across to the last st, 2dtr into the last st. (109 sts)
Row 48 (RS): Standing htr into the first st, htr into same st. Htr into each dtr across. Sl st into the third loop of the next 4 htr of the tree rings slice. Turn. (110 sts - 4 sl st do not count as sts)
Row 49 (WS): 3dtr into the last htr of row 48. Dtr into each st across to the last st, 2dtr into the last st. (113 sts)
Row 50 (RS): Standing htr into first st, htr into same st. Htr into each dtr across. Htr into the tree rings slice, into the last st you sl st to. Sl st into the third loop of the next 2 st on the tree rings slice. (117 sts - including the last 2 sl st)
Fasten off.