Single Edge Razor Blades Explained: Half-DE vs Injector Blades

Two razors can both be called single edge and take blades that will not fit each other. If you have bought the wrong refill once, this is why.

The short answer

A half-DE blade is an ordinary double edge blade snapped in two. An injector blade is a thicker, stiffer blade made for a specific loading mechanism. They are not interchangeable. Check which one your razor takes before you order.

Half-DE, also sold as single edge blades

Start with a standard double edge blade, the kind that fits almost every classic safety razor. Snap it across the middle at the scored line and you have two half blades. Some brands skip the step and sell them already halved, which is what you are buying when you see 100-count half blades.

Razors in this family hold one half blade in a head that is open on one side only. The NATU Single Edge Safety Razor works this way. Blades load magnetically, and because the format is not proprietary you can use any brand you like.

What we stock for it: Perma-Sharp Half Blades, 7AM Hi-Platinum Half Blades, and the rest of the half blade and single edge range.

Injector blades

An injector blade is a different object. It is thicker and stiffer than a DE blade, and it comes in a cartridge that pushes the new blade into the razor and ejects the old one in the same motion. You never touch the edge.

The Parker Adjustable Injector Razor is the one we sell. It ships with 20 blades, and refills are Parker Injector Razor Blades. Sharpologist covers the razor in detail in their review of the v3, including the point about injector blades being stiffer by nature.

If the history interests you, we wrote about the injector razor and why it came back.

Why the confusion exists

Both formats get called single edge, because both present one cutting edge to your face. Retailers file them in the same aisle. The blades even look similar in a photograph. The difference is thickness and how the razor takes them.

How to tell which one you have

• If the head opens and you lay a blade in, it takes a half blade.
• If there is a slot at the top and a key or cartridge pushes a blade through, it takes injector blades.
• If the razor is adjustable with a dial and no doors, it is almost certainly an injector.
• If in doubt, look at the blade you took out. A half blade has one straight snapped edge. An injector blade is a solid rectangle, noticeably stiffer.

Cost, honestly

Half blades are the cheaper of the two because they start life as ordinary DE blades, which are made by the million. Injector blades cost more per blade but tend to last well and the loading is the easiest of any razor format.

Disposal

Both go in a blade bank or another puncture-resistant container. Never loose in household rubbish.

Still not sure?

Tell us the razor and we will tell you the blade. We are a family business in Montreal and we would rather answer an email than sell you the wrong refill.