This protective brief has a leak-proof lining from the gusset all the way to the waistline to prevent any unexpected leakage. Certainly a godsend for menstrual period, post-partum bleeding or for ladies with incontinence / weak bladder issue, no more mess on mattress or embarrassing stains on clothes. Direction: This protective brief has a waterproof lining to guard unexpected leakage. The leak-proof lining has no absorbent feature and must be used together with sanitary napkins or incontinence pads. There are two different types of waterproof lining: for size US 10 - 22, the lining is made of cotton lined with synthetic fibers, for size US 0 - 8 the lining is made of synethic fibers. Care instruction: Synethic fibers could possibly be damaged by high temperature, we recommend machine wash cold, no tumble dry, do not bleach/or use non-chlorine bleach only, and do not iron. Note: Size name refers to Clothing Size, not panty size.