Adrian Bayer, the founder of MMB Monostahl (Messer & Mechanik Bayer), is himself an absolute knife passionate and also likes to use the knives quite hard. So it came about that he built a pocket fixed one day himself, as all folding knives did not meet his ideal of being robust enough.

Adrian’s products are supposed to be robust, versatile and compact. Wir haben es getestet und waren nicht schlecht erstaunt, was diese kleine Taschenaxt alles wegstecken kann. Die Messer werden in einer Kleinserie hergestellt und unterscheiden sich alle ein wenig voneinander, da Sie alle mit der Hand aus dem vollen geschliffen werden. Es sind keine Vitrinenmesser, sondern sie sollen benützt werden, dass ist auch genau unser Motto. Für Kunden die hier mit der Lupe kleinen Fehler suchen sind diese Messer nicht gebaut, sondern als Backup und Allroundhelfer und für die besonderen harten Fälle. Wir haben ein Test gemacht, welchen Sie sich hier ansehen können, bitte aber nicht nachmachen. Da es wirklich darum ging die Grenzen auszuloten, wie weit wir gekommen sind, sehen Sie hier im Video.

Made in Germany / Black Forest
The knives are delivered with a certificate in a box.

The 4034 steel by Adrian Bayer:

I grind each of these knives completely by hand from the forged blank. Every surface must be ground several times from all sides. That is why this knife is not a mass-produced product, but handmade in the Black Forest.

About the steel:

The 1.4034 is a blade steel that can be forged well in the die and, with good heat treatment, does not have any real weaknesses, but it does not have high peak values or a fashionable designation.
It can be brought back to a good sharpness with the simplest of means. With good heat treatment, a good hardness value of approx. 57HRC can be achieved with still good toughness.
To this day, and probably also in the future, various cutting tools are made with it, from hunting or razor knives to surgical knives with 20 cm blade length, also by large manufacturers.

The “designation problem”:
The 1.4034 is traded in the USA, for example, as “420C” and not as “420” because it has a somewhat higher C content, approx. 0.43 – 0.5 %. Due to the chromium alloy with 13 %, it is supposed to behave similarly to a carbon steel with approx. 0.8 % C. The “normal” 420 in the USA, however, would also correspond to the DIN designation 1.4028 or 1.4031, for example, both of which have less C, however. This is how misunderstandings arise.

Here is a list:

Designation: EN-DIN – AISI:
1.4028 – MO 1.4028 – 420X (+Mo)
1.4028 – YC, YN 1.4028 – AISI 420, 420B
1.4031 – YA ~1.4031 – AISI 420
1.4031 – YC, YE 1.4031 – AISI 420, ~420X
1.4034 – YN – 1.4034
1.4034 – YS, YE, YK 1.4034 – AISI 420, 420C
1.4035 – YU 1.4035 – AISI 420C (+S)
1.4037 – YR 1.4037 – AISI 420

You can see the different DIN/EN standardisation of the steels, but not always so with the US designations, they could all just be called 420 and it wouldn’t necessarily be wrong.

Additional information

Weight 0,400 kg
Blade thickness (mm)


Blade length (mm)


Weight (g)

170 with sheath

Blade height (mm)




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