One of the new features implemented on the fourth iteration of the Merrel Mix Master series is the external rear sling lock in the heel. This is intended to heighten the support and security within the platform for uninterrupted running performance. 

The EVA sockliner of the running shoe is now made changeable, permitting orthotics for those who want added support. 

The rest of the trail running platform's composition mirrors that of its predecessor. For instance, it still keeps reflective details for better visibility during low-light hours.

Size and fit

The Merrell Mix Master 4 is configured using the standard sizing scales for both male and female runners. This means that they can purchase the trail running shoe following their usual size preference. 

One of the aspects of the Mix Master 4 that influences its fit is the mesh and TPU upper of the platform. The combination of these two upper materials provides optimal fit and flexibility for unrestrained foot motions. Meanwhile, the external rear heel counter secures the foot in place, preventing slippage. Lastly, the EVA insole embedded within the foot chamber enhances the fit and support for better stability.


Equipped with M Select Grip outsole, the Merrell Mix Master 4 is geared with reliable surface traction. This is especially helpful in maintaining surefootedness on the unpredictable trail paths. It also protects the foot from impact as it offers superb impact mitigation. It also heightens the strength of the platform, impeding wear and tear, given the rugged terrains.


Comprising the midsole of the Mix Master 4 is an EVA foam. It is made up of TPU pellets that highlight rebound and cushioning. Because of its engineering, the EVA midsole gives the underfoot a plush yet bouncy sensation for maximum efficiency in each stride. More importantly, this midsole element is configured to have a lasting operational function. The same midsole component is found in the Hoka One One Bondi 6.

Complementing the EVA midsole foam is the shoe's EVA footbed. It permits a smooth underfoot feel that's essential in yielding lasting performance. It also pronounces foot support within the foot compartment for an even distribution of pressure, preventing strain on the muscles.


For the upper of the Merrell Mix Master 4, it sports a blend of mesh and TPU materials. Together, these create an irritation-free, lockdown wrap around the foot. It also reinforces the upper because of its sturdy build without necessarily sacrificing comfort. Because of the perforations employed by the upper of the running shoe, breathability is amplified for a healthy foot nature. 

To encourage better visibility when running during dim hours, reflective details are bonded to the upper. 

Meanwhile, a traditional lacing system is included in the upper composition of the shoe for an adjustable fit. To highlight security even further, an external heel counter is introduced to the platform's design. It locks the foot in place through the entire gait cycle.


The current trend of Merrell Mix Master 4.
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Jens Jakob Andersen
Jens Jakob Andersen

Jens Jakob is a fan of short distances with a 5K PR at 15:58 minutes. Based on 35 million race results, he's among the fastest 0.2% runners. Jens Jakob previously owned a running store, when he was also a competitive runner. His work is regularly featured in The New York Times, Washington Post, BBC and the likes as well as peer-reviewed journals. Finally, he has been a guest on +30 podcasts on running.