Crest 3D White Whitestrips Professional Effects gives you long-lasting, professional-level whitening. These whitestrips arethin, flexible strips that are coated with a tooth whitening gel containing peroxide. Designed to conform to the shape of your teeth, they work by keeping the whitening gel on your teeth for 30 minutes once a day to get at stain build-up on and below the tooth's surface. Apply once a day for 30 minutes. you'll start seeing a whiter smile after three days, with full results in 20 days. Features: PROFESSIONAL TEETH WHITENING AT HOME. RESULTS LAST UP TO 12 MONTHS. APPLY ONCE A DAY FOR 30 MINUTES. ADVANCED SEAL TECHNOLOGY NO-SLIP GRIP STAYS PUT SO YOU CAN TALK AND DRINK WATER WHILE WHITENING TEETH. USES THE SAME ENAMEL-SAFE TEETH WHITENING AGENT DENTISTS USE.