We guarantee the lining is 100% leak proof.  Customers can test the lining by pouring water on the it, you will see the outer fabric remains dry and neat.  

Something you should know: This protective underwear does not replace pads or tampons and should not be use as alone product.  The leak proof capacity is for providing protection against unexpected leakage overflowed from pads or tampons.  You still need to use pads or tampons.

Care instructions:

• Before Initial Use: Machine wash cold with detergent
• Stain Removal: Very easy wash-off, throw into washing machine and put some detergents, viola, it's clean as new. 
• No Heat Please: The waterproof lining is made of cotton lined with synthetic fibers, which could possibly be damaged when exposing to extremely high temperature for prolonged period. Just go easy and wash the brief as you normally do.

• LEAKPROOF PROTECTION: Mid-rise women protective underwear with frontal and extra wide rear protection to guard unexpected leakage overflowed from pads or tampons, no more mess on mattress or embarrassing stains on clothes
• RECOMMENDED FOR: Menstrual cycle heavy flow, postpartum bleeding, fecal and urinary incontinence, postnatal recovery, weak bladder control
• INSTRUCTION: Please note the cotton-blend leak proof lining is NOT for absorbency, it serves to prevent liquid going through only, MUST use with sanitary napkins, tampons, pantyliners, menstrual cups, maternity pads, incontinence pads. It also holds well for gel packs or ice packs for hemorrhoid pain relief.
• SIZE RANGE: From S up to 6XL, from petite to plus size, the number listed in the size selection refers to clothing size
• OPTIONAL FEATURE: New style with pocket for holding extra pad to change in public discreetly (color name indicated "w/ pocket")