Case of 4 Kits; each kit containing the Crest Prof. Whitestrips (42 strips/21 treatments); LED Light INSTRUCTIONS TO USE • APPLY. Peel the upper and lower strip from plastic backing liner and apply strips to upper and lower teeth. WEAR FOR 60 MINUTES. DO NOT REMOVE THE TEETH WHITENING STRIPS YET. • HOLD. To start the light treatment, press and hold the two buttons on the sides of the device simultaneously to turn on light, then release. • LIGHT. Place the light against strips for 5 minutes. Light will turn off after 5 minutes. Then remove the light and strips. Peel strips from back of teeth first to ease removal. • SMILE. Reveal your whiter smile. It is best if you do not brush your teeth immediately before applying strips.