Black vinyl with white adhesive paper label attached after the record was pressed. This was made by Iberofon as a preview test pressing for DGC. It was pressed on the high pressure pressing machine described on the Iberofon page, which is why the labels weren't heat-pressed as usual. They would have burned up. Records pressed using this machine were also thicker than most vinyl records, see image 2. The matrix codes miss a part usually included on Iberofon pressings for production, this was not included as it was just a preview for the record label.  The matrix codes are also unusually unsmooth.
The B-side is not the same as on the retail issues, which was Endless, Nameless. The production tape (see images 4-6) came with technical information for the engineering, and a sheet with full details for the test pressings and a possible later production. This test pressing was eventually rejected by DGC, and they decided on Endless, Nameless instead. Ten copies were made, and all were returned to Iberofon for recycling. An employee kept one copy, the remaining nine were destroyed. 
2. Vinyl thickness
3. Test pressing matrix (top) compared to Smells Like Teen Spirit (GES 19050 (1A)) retail matrix (bottom)
4. Production reel box with Iberofon label
5. Production reel
6. Instructions included with the production reel