
They are absorbent fabric patches that you attach to the inside seam of pants, jeans or tights. They act as a replacement to underwear and leave no panty lines or uncomfortable chafing (the pads are incredibly soft, you hardly notice them at all). It's almost like attaching a pantyliner to the inside of your jeans, minus the uncomfortableness. They also stay in place quite well, whereas a pantyliner won't. They even come in organic cotton.
Unfortunately, there is a downside. Cost-wise, they're a steep $16 - $18 for a package of 8.