NHL series helical gearboxes are designed making use of a very high degree of modularity, obtained by composing a structure of kits of the main sub-groups, in order to give rise to the different configurations of the final product, fulfilling the specific needs required in a specific application. Modularity brings even meaningful advantages for the distribution network, both in terms of timing for the supply of the product to the end customer and in the optics of the optimization of warehouse investments.