The side straps on Freemotion harness 5.0 and Combined Harness can easily be changed.
Freemotion comes with static side straps as standard, Combined with elastic. These can be replaced with elastic or static straps. The elastic straps gives your dog an advantage when it comes to its movement, gaining some extra centimeters each stride. This is why many prefer these straps, including mushers and canicrossers.
Over time the elastic straps will lose their resilience. See the side straps. Static straps are more durable.
To change the strap, loosen the buckle on the side of the harness. Pull the strap through the webbing canal and out of the plastic buckle. Thread the new strap into the plastic buckle, through the webbing canal and to the buckle.