FORMULA is the new generation of automatic machines, which integrates the innovative technologies of the double-ring moulding system patented by STEMMA for soles with three layers or three different densities. Soles produced for polyurethane double injection matched with a pre-moulded tread in rubber or TPU (PLUS2 technology), or, as per the latest innovation presented, made using a single integrated process (SWAP system) with tread obtained through TPU pouring or by polyurethane injection or spraying.  Technologies, which, thanks to their potential, have found their best application in the production of technical footwear and especially safety shoes. They in fact allow the features of the sole to be optimized, combining the specific properties of the materials used between them (e.g. hardness, rebound, lightness), to create shoes with an innovative design, with new aesthetical and functional solutions in which the polyurethane of the sole is integrated with the upper to create protections or stiffening elements. The solutions developed by STEMMA stand out for the productivity and efficiency, which remain unaltered when compared to traditional dual density productions. The processing units are perfectly integrated in a completely automated system, which allows less manpower to be used, while guaranteeing high technical and qualitative standards for the product.