The remote fillers I have seen advertised are a flat peice of aluminum plate about 3/8" thick with an o-ring groove milled around the perimeter so that the o-ring sets directly above the perimeter of the master cylinder reservoir. There is a clamp which holds the plate securely in place and compresses the o-ring, so that nothing can leak. there are 2-small diameter pipes (tubes) coming out of the top of the plate, one over each side of the reservoir (if it is a divided reservoir master cylinder). There are flexible lines that lead from these tubes to the remote filler, which is simply a small billet reservoir with screw on caps and a flange for bolting to the firewall (or where ever.)---These remote filler 'kits' will work for under-floor master cylinders also.