I recieved the information package from Tides Marine the other day. Looks like decent product and is priced CONSIDERABLY less than the Harken system. They include five measuring discs in the package for determining which track shape is necessary for your mast (about 35 options!). The track is made from UHMW-PE and can be shipped in seamless lengths up to 65 feet. Cost is less than $30 a foot INCLUDING hardware. Does not mention sail modifications which I am particularly interested in.