Dry is the slim front pad it catches drips and sweat, and fixes to your underwear with a skin-safe adhesive strip that grips the fabric, never your skin, and removes cleanly.
Shield is the contoured back pad it handles sweat and marks, and needs no adhesive at all: its shape sits in place, held by your body's natural pressure. Same idea, different geometry. Wear whichever fits your day, or both together: they're designed as a pair