I have been shaving using Panasonic electric shavers (recently: Panasonic ES8101S Electric Shaver, Panasonic Pro-Curve ES7037) for over a decade, because I had too much irritation when I tried to use Gillette shavers when I was a teenager. Recently, I tried Gillette Fusion, Gillette Fusion Power and Gillette Fusion ProGlide and discovered I could get a much better shave with them, albeit with some irritation. To get a better shave than what an electric shaver gave me but with less irritation, I decided to give double-edge (DE) safety razors a try.
I got a Parker shaver and Shark Super Chrome blades, along with a badger hair brush and some decent shaving soap. The result was very good: close shave with less irritation that that provided by the Gillette Fusion variants. Still, I wanted to try different blades, since different skin and beard types respond better to different blades.
What is Derby Extra Blade
The Derby Extra blades are double-edge blades made of stainless steel with tungsten-platinum polymer coating for longevity. They are imported from Turkey (the Shark blades are from Egypt).
I bought 30 Derby blades and used 25 of them at this point. They are different from the Shark blades in three ways:
1. The blade seems to pull slightly more when the beard is longer than a day old. The blade might be less sharp than the Shark blade.
2. The Derby blade seems to glide over the skin better than the Shark blade when the beard is 1 day or shorter, resulting in less irritation and the ability to use more passes over the same area without the fear of irritating the skin.
3. The longevity of Shark blades seems to be better. The Derby blades last about 40% less than the Shark blades.
4. Shaving with Derby blades takes longer than with Shark blades because more passes are required, especially when the beard is more than a day old.
Be mindful that the results depend on the type of the beard and skin.
The blades come in packages of 5 in a plastic cartridge that, unlike Shark blades, has no used blade disposal slot at the bottom, so to dispose of the used blades, you have to remove all unused blades and insert the used blade, then put the unused blades back.
Compared to Astra Superior Platinum
I also got Astra Superior Platinum and although I liked them on first use, I was ultimately disappointed. Not only did Astra blades result in skin irritation on every single use, they also don't last as long as Shark or Derby and their packaging is frustrating to deal with.
After using Astra blades it was a relief to go back to Shark and Derby blades.
Compared to Personna Blades
Personna Blue blades seem to be sharper, smoother and last longer. They are my most favorites blades now.
At about 20 cents per blade, which lasts close to a week, these blades are much cheaper than Gillette Fusion, Schick Hydro 5 or Schick Hydro 3. They are better for environment too.
Pros: Low price, smooth, close shave, no pulling when the beard is short
Cons: Pulling when beard is long, no used blade disposal slot, Shark are sharper, last longer
Although I get a closer, less irritating shave with these Derby blades than that of the Shark blades if I shave every day, the Shark blades last longer and have a useful used blade disposal slot built into the cartridge. Shark blades also work better if I don't shave every day. Both kinds of blades have their advantages and disadvantages and I expect to be using both of them. In any case, I recommend that you try these Derby blades and see for yourself if your beard and skin respond well to them.