In 1939, Alexandre Horowitz, inventor at Philips, developed the first 'Rotary' shaving head. At that time, the shaver called 'Steel Beard' with only one shaving head. Nowadays, rotary shavers usually have 3 shaving heads, but there are also 2 header shavers. In the 50s and later, all kinds of inventors patented new ideas based on this invention. 

The double-ring shaving heads from Shaver-Parts are free of patents because the idea has actually existed already for a long time. At that time of inventions, it was technically too complicated to produce the shaving heads in mass production and at good quality. 
Shaver-Parts double-ring shaving heads have good shaving performance because each ring has a hollow groove, also called a "Concave groove"! In the middle part of each shaving ring of the shaving head, the thickness is a little thinner so that the beard hairs can be cut slightly shorter. Our double-ring shaving heads fits in many existing shavers that still have a single-ring shaving head, please check first what you need.

For more shaving-head alternatives, see the overview in the menu: Model Numbers
 

Model: A-N2
Below is our alternative shaving head as a replacement for: HP1915, HQ3, HQ4, HQ5, HQ55 & HQ56, Model: A-N2

 

Drive shaft (clutch) according to patent: US00000475998A (1987), 3 teeth.


Model: G-N2, HQ6 Lift & Cut,
NOTE:  
Philips HQ6 shaving head has 'hooks'; for this we also have an alternative with hooks, model: G-N2, this shaving head is equipped with the Lift & Cut principle. 
If you require an HQ6 alternative, first clean the holder well under warm water to remove the skin oil.  

 

Model: D-N2
Below, our alternative shaving head as a replacement for: HP1917 / HQ2 (successor of HP1917).
2 teeth driving shaft.

Model: D-N2 

 

Below is our alternative shaving head as a substitute for: HQ8 (HQ177), Model: B-N2

Model: B-N2  
NOTE:  
Philips HQ8 (HQ177). Shaving-head has 'hooks'; ours don't have that because they are universal but fit well. First, clean the holder well under warm water to remove the skin oil. There is then enough friction,
and then shaving-heads no longer rotates. 
Model: B-N2 

 

The shape of the plastic drive is not a patent because it is made according to the long-standing DIN 32711 standard.
 

 

Model: F-N2
Below are examples of old patents relating to double and triple shaving rings. The triple shaving ring from Philips, the HQ9, is actually not new but based on these old patents. Here again, Philips has a patent on making the cutter: the inner and middle cutter are combined and made from one 'plate'. 

Our HQ9 Triple, Model: F-N2, is technically built differently.

 

At that time, it was not possible to manufacture good quality in mass production. 

 

Other models: 

Model: E-N2 
HQ4 Lift & Cut, also for HQ5 HQ55 & HQ56, Model: E-N2 

 

Model: C-N2 
HQ167 & HQ156 (old Coolskin). Model C-N2 

 

Model: H-N2 
HQ8 Lift & Cut, also for HQ177 (Coolskin). Model: H-N2 

 

Model: U-N2 RQ32,

 

 

For more shaver head alternatives, see the overview in the menu: Model Numbers.