This forty-foot Strong Track is inserted into the mainsail slot on a mast. It uses stainless steel slides which makes raising and lowering the mainsail very easy. In fact, when you release the main halyard, the sail will lower itself. You can see one on my boat, walk 2, sip 26, or on several other boats in the club’s moorage. I am selling it because it would not fit my new mast. It comes with six slides, and you will have to purchase additional slides, depending on the luff length of your main. Price is $350, and I can measure your mast to see whether it will fit.