Original or compatible?
Shaving heads fit by series, not by brand: a Philips head fits the Philips series it is made for, a Braun cassette the Braun series printed on its pack. Genuine heads come from Philips and Braun; compatible heads are sold widely and name the original code. Each head's page lists the shaver types it fits.
Where the model number is
The type number is printed on the back or bottom of the handle, often in small print (S9987, SP9883, 9599cc, 51-B4650cs). The series name on the front (Series 9, S7000) narrows it down.
Why change it on time
Philips says to replace its heads every two years and Braun its cassettes every 18 months: blunt cutters pull rather than cut, and a worn foil can nick the skin. Many shavers show a replacement reminder.
How this list is built
Every fit comes from the manufacturer's own compatibility list or parts page, with the source recorded on each row. Where only a seller lists a fit, the page says so. Prices are re-read from each seller's page daily where they publish one, and dated. How FitMatch checks fitment.