I started this the other day on 2.5mm needles. I had most of the leg done when I realized it was just too snug. It's only 66 sts (multiples of 11 for the kitty cats). I knit it again with 2.75mm needles and that solved the problem.The pattern calls for an afterthought heel but it is not my favourite - it's easy but a bit fiddly. Instead, I did a short row heel., starting it halfway along the 8 stocking stitch rows between kitty cat heads.