Special techniques On some shoes, in addition to the classic processes described up to now, Calzaturificio Fratelli Borgioli uses special techniques. Flex construction Flex construction calls for an insole made of fine, thin leather rather than thicker shoe leather, giving the footwear extraordinary flexibility and comfort. Goodyear welt construction The welt, a long strip of sole leather, is sewn both to the edges of the upper and to the insole. The seam between the welt and the upper is hidden between the outsole and insole. This is the sturdiest, most laborious method of shoe construction; it is completely carried out by hand and ensures the premium quality of the shoe. Norwegian construction Three seams are needed to complete this complex process. The first joins the upper to the insole, and the second joins the turned-out edge of the upper to the midsole. So obviously, in this process, the edging around the perimeter of the shoe and of the sole is not created by the welt, but by an actual midsole. Then the outsole is sewn to the latter, to create a single body. This complex, fascinating method, ideal for customers who want solid, sturdy footwear, makes the shoe highly waterproof.