I think this fabric is just ripstop nylon. Not SpinnTex. Thur-Hiker states that SpinnTex EXP is "polyester rip stop". SailRite has a spinnaker fabric similar to SailMaker, but in 60" width:
The standard for spinnaker and drifter fabric! Nylite 90 Ripstop Nylon Black 3/4 oz 60" is a lightweight spinnaker cloth that has been resin impregnated for stability and coated for zero porosity. Ripstop sailcloth has a nylon weave construction that looks like a continuous series of small squares for an increased ability to prevent tears. Nylon ripstop has controlled stretch, zero porosity, and remarkable durability in use and in storage.
This Nylite ripstop is the most widely used for all-purpose spinnakers, asymmetrical racing spinnakers, drifters, staysails, and kites. Available in many great colors!
Width: 60 inches
Weight: .75 oz.
Spinnaker fabric doesn't mean it's SpinnTex