Benchmade Serum AXIS Dual-Action Automatic Knife G-10 (3.5" Black Serr) 5400SBK

MSRP: $270.00
Our Sale Price: $179.99!
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Item #BHQ-24211


  • Overall Length:8.17"
  • Blade Length:3.47"
  • Blade Thickness:0.12"
  • Blade Material:154CM
  • Hardness:58-60 RC
  • Blade Style:Drop Point
  • Finish:Black
  • Edge Type:Serrated
  • Handle Length:4.70"
  • Handle Thickness:0.58"
  • Handle Material:G-10
  • Color:Black
  • Frame/Liner:Stainless Steel
  • Weight:4.63 oz.
  • User:Right Hand, Left Hand
  • Pocket Clip:Tip-Up
  • Knife Type:Dual-Action Automatic
  • Opener:AXIS, Thumb Stud
  • Lock Type:AXIS®
  • Brand:Benchmade
  • Model:Serum
  • Model Number:5400SBK
  • Country of Origin:USA
  • Best Use:Tactical
  • Product Type:Knife


Marking the first application of the AXIS Dual-Action mechanism, the 5400 Serum is a notable addition to the Benchmade lineup. The AXIS Dual-Action mechanism functions like a regular AXIS lock for manual operation, but when the AXIS bar is fully pulled back the automatic mechanism deploys the blade. Benchmade has equipped the knife with a secondary safety system to eliminate "dry fire," which occurs when a blade isn't fully closed.

The Serum is a versatile setup with the ambidextrous AXIS Dual-Action mechanism, comfortably milled G-10 handle, and modified drop point blade. The 5400SBK has a black finished 154-CM steel blade with a partially serrated edge and black G-10 handle with a reversible tip-up carry pocket clip. This is an outrageously clever knife from the crew at Benchmade.

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Customer Reviews

Write a review for this item
Simply awesome
Greg D.
Love this knife. Perfect size for edc and tactical all in one package. Double action opening works great. I've seen a not so positive review on this knife saying the auto side of the opening feature was stiff and a little awkward. Mine was similar but with an adjustment on the pivot screw it works flawlessly. Easy to adjust for solid auto opening.
David G.
Got this for my collection, wanted a dual action. Definitely a conversation piece but to bulky for EDC. Blade nice and snug in manual opening, but a little wobbly with automatic opening. Strange but still like it for my collection.
Best Knife Ever
Zachary J.
This is my first benchmade and im enjoying it!
Auto Activation is Finicky
Jason D.
I ordered this knife with the intention of using it as a daily carry. However, I encountered 2 issues/irritations with the knife which ultimately made it not for me.

Issue 1: The dual activation mechanism can be finicky when using the auto feature. When you depress the axis mechanism down, it meets a wall. Once at the wall, you then have to continue pressing down to activate and release the blade automatically (it is a solid click feeling when done correctly). In order to do this successfully and repeatedly, I would have to press down on the axis mechanism with my thumb and index finger simultaneously from both sides fo the knife while also securing the butt end of the knife in my hand (this forces a modified grip of the knife to achieve). This may loosen up over time to allow for thumb only activation, but out of the box the thumb only auto activation was a pain. There is no manual safety on the "spine" or backside of the knife (only a built in safety feature) so this added depress requirement may be an added safety from inadvertently deploying the knife automatically in your pocket.

Issue 2: This is in regards to the auto activation not fully throwing the blade out. I believe this has to do with the built in safety mechanism to prevent the blade from flying back out when closing. If you close the blade, it can lock closed but not reset the auto portion of the knife. When you attempt to re-deploy the knife automatically, the blade will come only out 10-20% of the way and stop like it has no spring behind it. This is usually fixed by fully pressing the blade closed more than what is required to lock the blade closed or by cycling open and closed again in the manual method. This was happening regularly enough that concern was raised by myself and my colleagues handling the knife. The auto aspect of a knife should fire 100% of the time, not 75% of the time depending on how well you close it.

The manual deployment is on par with other non spring assisted Benchmade axis knives I have handled.

The finish of the G-10 handles are awesome and look amazing. The styling of the knife I really enjoy. The feel in the hand is excellent along with a nice balanced weight distribution. The build quality is excellent and everything you would expect from Benchmade

In summary, I feel this is is primarily a non spring assisted manual knife with a neat auto feature added to it, but not meant to be the primary deployment method. Under stress or when you would prefer the auto activation I am unsure if the knife would always deploy correctly which is ultimately why I am going a different route.

For a daily carry where the manual deployment would be primary, this is an excellent option. However, I was left preferring my spring assisted axis over this knife in every aspect when considering the manual deployment as the primary deployment option.