The Zip-Stop main hasn't been in production for a long time. This is why most people have never seen one. While an interesting concept, in use it was rather problematic. It is basically a full length zippered sleeve, that would encase the mainsail when not in use. The main had short battens and a loose foot. You would ease off the outhaul completely, pull the entire foot of the sail forward and pull down on the leech, then pull the zipper down. The zippers were a common point of failure. Roller Furling Masts have pretty much taken over where these left off.I personally haven't seen a zipstop main in our loft in about 10 years, and if I came accross one, I would recommend that IF the sail is still in good condition, that it be converted to conventional use. My two-cents!I think other sailmakers would give you pretty much the same opinion