The difficulty in securing the Mast Mate to a mast with an internal roller furling mainsail can be dealt with quite simply. First determine the width of the mast slot, then purchase a section of PVC tubing or hose with a diameter slightly larger than the width of the mast slot. Cut the PVC or hose in 3-4in pieces. While weaving a piece of 1/4in line through the grommets on the Mast Mate, thread a PVC or hose section between each grommet ( between every other grommet is adequate). Tie off 1/4in line on top and bottom of the Mast Mate and as you are raising the Mast Mate feed the line and PVC or hose sections into the widened portion of the slot at the goose neck. You can adjust the stiffness of the system by either loosening or tightening the line. Depending on mast design, alternative methods of attaching the PVC or hose sections to the Mast Mate may be possible.