Keep a close shave Every year, your blades travel the height of Mt. Everest... 49 times! After such a workout, even the best materials can lose their edge. Retain your shaver s peak performance - replace the heads once every 2 years. Comfortably close Super Lift & Cut shaving technology with dual blade system. First blade lifts, second blade cuts for a comfortable close shave. Shaves even the shortest stubble Precision Cutting System. Ultra-thin heads with slots to shave long hairs and holes to shave the shortest stubble. Fits Norelco product types: HQ6425, HQ6426, HQ6423, HQ662, HQ663, HQ664, HQ686, HQ7415, HQ7815, HQ7830, HQ7850, HQ7870, HQ7405, HQ7615, HQ7616,HQ7617, HQ7814, HQ7816, HQ7817, HQ7820, HQ7821, HQ7825, HQ7829, HQ7845, HQ7864, HQ7865, HQ7868, HQ7885 Does not fit any other Norelco models.