Karhu Fusion 4.0

The updated Karhu Fusion is now a plush and responsive trainer for neutral runners. A new IdealKnit mesh creates an upper that has improved breathability and comfort. The biggest change is a new nitrogen-injected AeroFoam midsole that results in notably increased rebound. Impact absorption is aided by the addition of a new deflection channel on the bottom of the midsole. The Fusion 4.0 has a shortened Fulcrum and a propulsion unit. Giving you comfort and response for all of your miles, the updated Karhu Fusion 4.0 is definitely a shoe to try out.

Fleet Feet's review of the Fusion 4.0