White label records were pressed when they warmed up the presses and adjusted the cycle times. They usually pressed around 15 records during this process. The last records were quality controlled until they passed. The copy shown below was the last copy tested, and is the only one in existence. It was kept by the quality controller, while the others were thrown on the floor and recycled. 
These test pressings were pressed before the MFSL label test pressings . The surviving white label copy came in the same white die-cut sleeve as the proper test pressings. Note that this is a test pressing of the A-1/B-1 cut, while the MFSL label test pressings are of the A-2/B-2 cut, at least the ones which have been found so far.
The lacquers were mastered at half speed by Ken Lee at Original Masterworks, as seen from "KL/2" in the matrix code . The two cuts may have been done individually, but more likely by two lathes working in tandem. The records were pressed by MoFi in Sebastopol, California.
1. Side A
2. Side B