This model is an add on piece compatible with any 65mm router ( like this one makita rt0701 ) and it allows you to add a dust collection system to your cnc machine without any complex parts. In fact this piece only required one M3 bolt and nut to be secured to your router, underneath the router holder. any 35mm vacuum hose like the karcher's one is compatible with this setup.
Adding a vacuum cleaner to your cnc reduces the amount of dust generated by your router, keeps your bearings and other mecanical parts clean.