This is from Polymer 80. They claim:

"This product was created for compatibility with milspec 80% AR15 lower receivers no matter whether they are polymer or metal. The Universal Jig is designed with a super rigid long-fiber nylon composite, which will allow the customer to utilize the jig up to 3 times. This low-cost jig is the perfect alternative to the expensive and more complicated metal jigs, especially if you’re just planning on building a few AR15 lowers – why pay more?"

http://www.polymer80.com/ar-15-lower/rj ... versal-jig

I ordered one. We shall see how it works.

That looks like the jig and bit set that comes with the Polymer 80 kit. If I knew you needed one I would have sold you an extra complete kit with lower for 60. Hard to say how well it would do with an aluminium lower. If you are doing it on a nice mill or something it would probably be OK. I am certainly no machinist.

Thanks. I already have a couple Poly 80 kits, but haven't got around to finishing them. The description on this sounds like a different kind of jig. The normal Poly 80 jigs are supposed to be one time use.