Zimmerli Business Class Open Button Fly Boxer (2221477). The Zimmerli Business Class Open Button Fly Boxer 222-1477 has a secure button fly at front with a fit-improving gusset at inseam and seam-free rear. A combed long staple cotton body makes it worthy to be called the world's finest underwear, produced since 1871 in Switzerland. Zimmerli's Business Class Open Button Fly Boxer is made of 100% cotton.