Let me guess you bought it from a canadian guy? He misidentified his skimmer ordered the wrong mounts, had the proverbial $h12 fit and put it up for sale. That is a 235/2 skimmer and requires a set of fiberglass rails that slide into the sides and then mount to a brace set up on either side of the sump or across the trim of the tank. Unfortunately it is very difficult to ship to and from Canada and expensive so it was not possible to resolve this to his liking. If the mounts are unused and unopened I would credit a return toward the rails which are not to expensive but it is not exactly cheap to ship 1m lengths of fiberglass, they are oversized, I do have them in stock and with a little ingenuity something could be fashioned out of acrylic or eggcrate to support the skimmer. If you PM me I can send you a PDF of the manual- include your email address.