Hello I'm going to buy 2 units of Electrolux Chill Flex Pro (12000BTU/h) but I'm in doubt regarding which exhaust system to buy (flexible ducts and connextion on the system and window) since several option are highlighted in your website (cheap and expensive ones). My windon open about 30 degree upper side , and has the dimension 150cm width and 82cm height Thanks in advance and waiting for your feedback P.S.: My company, JJ Cooling Innovation SARL will be paying for the product and thus potential I must register in your system, right?