Axles are a great way to tune your kart. Use a softer axle to gain more grip or try a harder axle to free the kart off turns and keep your lap times at their optimum at the end of the race.
The Kartech H2 is unique in that it has a thin wall of 2mm. This axle has proven to be a great all round axle for many different tyres and grip levels. In terms of overall grip level it sits between a soft and a medium grade 40mm axle. 

AX40H
AX40DM1-B
AX40HCSX.1M
AX40XXXS------