Hello, this product has different shaving heads in pictures 5 and 6. Are they shaving heads as shown in the picture with packaging, as in picture 5? Are these shaving heads with tabs, as my old shaving head says Series 8? Many thanks for any information. I would like original shaving heads from Philips with tabs like the existing Series 8. I have no designation on the shaver as it is older. I can't find the difference between round and square blades anywhere.