Save your money. The listing is crammed full of very questionable information aimed at folks that don't know anything about sails or sailing.
First of all - There ain't no such thing in sailmaking as "Free Flow Design". It's total B.S. I don't know whether they've coined that little phrase to justify the loose-footed bottom edge or the fact that it has a non-roached leech that requires no battens but it's meaningless marketing hype.
Ripstop nylon is a terrible choice for general-purpose sails as it has too much stretch. It's used for downwind sails (spinnakers, V-sails, etc.) where the sail doesn't need to hold it's draft in a specific location. When you try to make a jib or mainsail from it, your upwind performance goes right down the drain because it won't hold the designed (desired) shape. It's also rather fragile for that type of sail.
Nobody in their right mind would build a bermuda-style sail with that type of aspect ratio (height vs. length along the boom). It's an incredibly inefficient use of your sail area, as wide along the foot (bottom) as it is tall. The result = minimal lift, not much power and a boom that drags it's tail in the water as soon as the boat heels a bit. It also moves the Center of Effort way aft. Assuming that the daggerboard of the boat shown is either placed through the middle seat or a well just in front of it, the sail's C.E. is located just about straight above the aft edge of the middle seat when it should be about a foot forward of the daggerboard for a boat that size. This pretty much guarantees that the boats balance will be all screwed up and it will have horrible weather-helm (always trying to turn upwind, so you will be dragging the rudder through the water sideways just to try to correct the steering and get it to go straight).
I don't know anything about the seller or their business but this just can't be considered a serious attempt to build a sail and doesn't convey even a basic understanding of what goes into one.
