N.O.S. Gillette Techmatic from 1966, original cartridge, second blade position (9). Ninth shave with this blade and still getting a close, comfortable shave.
Skin guard 19
I have to admit...when I switched to a new cart I got a lot of irritation and ingrowns...this used one might not give me very close shaves but NO irritation....
SkinGuard Gillette #20 (head shave this time). Still going-- I tend to use the vibrating handle from the 5blade system; though in UK they sell it on the Skinguard (seems more potent BUT doesn't have the pivoting ball). Not sure if there is much difference or if all is psychological effect.