I got these pink hipster undies in a size 3x/4x and they are a bit too big for my bum, but they still work out for me. They don't ride up or roll down they are loose in the butt though. They are made for Seven 'til midnight (one of my favorite companies) and they arrived in clear plastic cellophane no hanger no packaging or anything fancy.

The panties are made of nylon and spandex but there are no care instructions any where on the panties. So I assume that we hand wash cold water no bleach and line dry. I did put them in a garment bag and wash them on delicate cycle in my washer and they came out a bit frayed but since I have a back up pair I received as a gift I am not upset about it.

The panties are see through but they have a solid piece in the front and where the panty liner is. The sides and butt are lace see through and have a flower pattern on them. They ride a little bit up on your butt cheeks just enough to show a little bit of flesh not a whole lot and not to the point of being uncomfortable either.

the sizing chart is for Seven 'til Midnight Size chart:
Cup Bust Waist Hip
Small 2 - 6 A - B 32 - 34 24 - 26 34 - 36
Medium 6 - 10 B - C 34 - 36 26 - 28 36 - 38
Large 10 - 14 C - D 36 - 38 28 - 30 38 - 40
X-Large 14 - 16 D - DD 38 - 40 30 - 32 40 - 42
Sm/Med 2 - 8 A - B 32 - 36 24 - 28 34 - 38
Med/Large 8 - 14 C - D 36 - 38 28 - 30 38 - 40
1X/2X 16 - 18 D - DD 40 - 46 36 - 38 42 - 48
3X/4X 20 - 22 D - DD 46 - 50 40 - 44 50 - 56
(I hope that looks ok).